Bosch: Oh! That's it!
That Dreamstone is all I need in
order to repair the Grandleon.
But the Grandleon, and now
Dreamstone... how did you...?
Oh, never mind.
Wait a little while.

Everyone goes downstairs. "Corridors of Time" plays. Crono can walk around and talk to Bosch and his assistant.

Bosch walks over to a bookcase and starts reading.

Bosch: I'm looking something up now.
Don't speak to me.

Bosch finds what he was seeking.

Bosch: In order to repair the Grandleon,
it is essential to not only refine the
Dreamstone but also activate the sword.
You refine the Dreamstone for me.
I'll carry out the activation of the sword.

Lucca: Got it!
Leave it to the great Lucca!

Bosch: In order to activate this sword, I must
breathe life back into the sword's substance
now that it has broken and lost its power.

Bosch: The spell to make the sword
activate is advanced and difficult.
Would you not speak to me for a while?

If he's using a spell, then he must be able to do magic, yet he also seems to be human... curious.

Lucca: Hrrm, this is a lot of trouble.
You're distracting me, so go away!

Robo: We lack the equipment, SO it seems
the purification WILL take some time.

Bosch: All right, I've finished.
Would you bring me the Dreamstone?

They begin. There's a bright light and a shrill noise... The scene cuts to back upstairs, with "Memories of Green" playing as usual.

The internal storyline progression tracking variable is now 0x81.

The lights dim as the character who assisted Bosch holds up the repaired sword.

Bosch: Behold!
THIS is the Grandleon!

Marle: AWESOME!
This is the Grandleon!?

Lucca: This is the Grandleon...
Energy unknown to me is coming from it.
It arouses my desire to investigate...

How can Lucca respond here if Bosch's helper doesn't speak and Lucca always volunteers to be Bosch's helper if present? Start the scene with Marle and Robo in the group, then swap Marle out for Lucca downstairs. Sneaky. Also, the NA version translation bugs me, and not just because it uses "it's" instead of "its". Does it make much sense for someone who has been using magic for some time to speak of being skeptical of the supernatural?

Robo: It IS mysterious.
I CAN sense spiritual energy
from this Grandleon itself.

Bosch: Well, that's just how things
go once you get me involved.

Marle: Well, Crono, let's bring the
Grandleon to Frog, quick!

Lucca: Well, Crono, we're bringing
the Grandleon to Frog, quick!

Robo: Well then, Crono, LET US
go to hand the Grandleon
over to mister Frog.

Bosch: A sword may be either a means
of taking life or a means of saving life,
depending on how the user's heart is.
Be sure not to misuse it.

Bosch isn't the only one who's been busy lately. Stop by here after fixing the Grandleon.

Taban: The great Taban's great invention.
The perfect armor for Lucca!
Use it well!

Frog is still here, as gloomy as before.

The party shows him the sword. The music stops dead.

Frog: This sword, it can't be...
the Grandleon...!?

Frog: This sword...
'Tis the Masamune?

Frog: ...let me think things over.
You can rest here tonight...

Frog: I must ponder this turn of
events.
Remain'eth here the night.

Fade out, then fade in to a flashback, in Guardia Castle. "Courage and Pride" plays. An unfamiliar knight stands in the throne room.

Leene: I see you're going.
Cyrus...

Cyrus: Yes. I've been thinking it's about
time someone retakes that badge from
that Golden Frog character...
I also want to try confirming the so-called
legendary sword with my own eyes...

Guardia: Cyrus, you are an
indispensible man to this country...
and also an irreplacable friend
to Leene and myself.
Be sure to come back.

Cyrus: Certainly, as long as I have life.
Even should something happen to me...
Well then, I take my leave...

Cyrus leaves the throne room, and Leene stands to watch him go. An assembly of soldiers awaits him outside.

Soldiers: We, the Royal Knights, all of us!
We are all praying for our
leader's safe journey...!!

SOLDIER: We, the Knights of the Square
Table, wish you a safe journey!

CYRUS: I now entrust the safety of the
kingdom to you!

Cyrus walks to the entryway, where a young man waits.

Cyrus: Sorry to keep you waiting.
Now, shall we go?

Queen Leene walks out.

Leene: Glenn!
You be careful too.

Glenn: May her lady the Queen
also remain in good health...

The scene changes, and "Battle" plays. Cyrus, wielding a red sword, fights off monsters in a forest, along with Glenn. The scene changes again, and "Boss Battle 1" plays. Now, Cyrus, accompanied by Glenn and an unknown young woman, faces a giant frog wearing a crown and flanked by two smaller frogs.

The big frog is monster ID 174, the Great Frog King (Frog King), but never appears in actual combat.

Cyrus: Naturally, allow me to do so.
Here I go, G-Frog!
Nirvana Slaaash!

Cyrus jabs at the frog several times quickly. It shrieks.

The frog tosses the badge to the ground and leaves with the lesser frogs. Cyrus takes the badge. Scene change to an unknown, dark location. Wind howls, and we hear sounds of combat.

More fighting noises, and a sound like something shattering.

Glenn: Cyrus!
The sword...!?
The Grandleon...!!

The screen scrolls up and lightens enough to show Cyrus and Glenn standing on a mountainside, facing Vinnegar. Behind Vinnegar stands a man with pale skin, long pale blue hair, dark clothes, and a navy blue cape that billows in the breeze. He seems to be paying no attention to the fighting behind him.

Vinnegar: Kya ha ha, what's the matter?
Finished already?
With the legendary sword broken,
I'll bet you can't do a thing!!

Glenn: C-Cyrus...
I c-can't...

Cyrus: Listen, Glenn.
I'll hold them off.
Run away then, even if it's just you.

Cyrus: At this rate, we'll both
be done in...
Go, Glenn.

The mysterious figure finally turns around. He drapes his cape around himself, and I think he looks a lot like a vampire.

Magus: Such composure, Cyrus, was it?
Is this any time to worry about another...?

Cyrus: Got it, Glenn?
Here I go!!

Cyrus: Graaaah...!

Cyrus charges the Magus, who casually fries him.

3-05 ジール宮殿 (Zeal Palace) starts playing.

Cyrus: R... run away...
Glenn...
The Queen...
Take care of...
lady Lee...
......

Glenn: C... Cyrus!?
Cyrusss!!

Cyrus bursts into flames and disappears.

Magus: Hmph, what's wrong...?
Aren't you going to attack?

Vinnegar: Gyo heh heh...
Like a frog caught in a snake's glare.
Youngsters these days.
How about it, O great Magus?
Why not turn this coward into
a more suitable form?

Magus: Hmph, very well...
I abolish all those who stand in
my way, without exception.

The Magus gestures, and a bolt of energy strikes Glenn. He starts glowing weird colors.

Glenn: Wh... whoaa!!
Gwaaaaa...!!

Glenn falls off the cliffside nearby.

Vinnegar: Gya, ha ha ha ha...!
You damn spineless worm...!

The scene changes back to the present, in Frog's dwelling in the woods. Everyone is asleep but Frog. "At the Bottom of Night" plays.

Frog: Has it already been
ten years since then...?
Can I do it...? Me...?
Cyrus...

The screen fades to black, and the music stops.

The screen fades in, showing everyone now awake. "Frog's Theme" fades in.

Frog: I don't know how much I'll be
able to do... but let's try going.
To Magus Castle...
He's strong...
Are you ready...?

The internal storyline progression tracking variable is now 0x84.

Clearing the game at this point leads to the alternate ending "Vow to a Friend".

Frog has joined the party, and is a required member until further notice. His equipment and skills are the same as before, but he's gained some levels. It's time for a few side trips, and not just for better equipment...

Specchio said to bring other people, so the party takes Frog here.

Specchio: This's another weird one
you've brought.
As you might guess given this guy's
a frog, he's got Water power.
Hanyaharahettamitaai!!

Frog flexes his muscles as water splashes around him. "Fanfare 3" plays.

Frog immediately learns ★ウォーター (Water), and, like the others, can now continue learning techniques normally.

As usual, Gina is here.

Gina: .........
Crono...
We can't keep such a large
pet in our home.

This line plays 蛙 (kaeru, frog) and 飼える (kaeru, able to keep a pet) against each other.

Frog: G... good lady.
I am not a pet. Though my form may
be like this, I'm a full-fledged soldier.

Gina: Oh, I'm sorry, mister Soldier.
I could have sworn...
I'm truly sorry, mister Soldier.

Her katakana ブジン (BUJIN) and appended さん (san), and his response below, seem to suggest she assumes 武人 (bujin) is his name. That makes some sense, since she may not recognise this older and less common term for a soldier (or more literally, a "military man" as opposed to a "scholarly man").

Frog: ......
Soldier is good enough...

The Magus's army is said to come through a cave here, yet there's nothing visible but a plain cliff. Frog steps forward and pokes at the cliff for a bit, then "At the Bottom of Night" starts playing, and the screen fades into another flashback. In a forest, four young boys dash around a fifth, who is spinning uncontrollably.

An older boy runs up, scaring the four who are running around.

The four of them run away, leaving the fifth still reeling. Cyrus steadies him.

Cyrus: Look, Glenn, a man's got times
when he has to fight back, too.

Glenn: But... getting hit hurts.
Even for them...

Glenn's saying that even they hurt when you hit them—in other words, that he doesn't want to hurt anyone—not that their blows hurt him.

Fade out, and fade in to a bridge. A man stands there, looking out at the sea. A young man walks up to him.

Cyrus: Hey, Glenn...
I'm thinking I'll join the Knights.

Glenn: I knew it!
I'm sure you can become a great knight.
I guarantee it.

Cyrus: Really.
I think your sword skill is the better.

Glenn: I'm hopeless.
I'm sure I'd freeze up in a real battle.

Fade out, then fade in to the mountain where Glenn faces the Magus and Vinnegar alone after Cyrus's death.

The Magus gestures, and a bolt of energy strikes Glenn. He starts glowing weird colors.

The scene fades out as Glenn nears the cliff edge, then fades back in to show Frog, washed up on a riverbank lower on the mountain. Something round and shiny drifts down the river and stops in front of him.

: The badge...
...of the... hero...

The...Medal.
...The Hero's...Medal...

This is as good a time as any to mention that カエル, the name he uses, is not just "frog", but also 変える, a verb meaning to change or transform. Additionally, in what is unlikely to be a coincidence, "Glenn" bears a certain resemblance to "grenouille", the French word for a frog.

The scene fades out, and we're back to the present. Frog turns around.

Crono dramtically stabs the sword into the ground (note that you shouldn't actually do that with a sword, as it can dull the edge) and walks out of the way. Frog steps up to it, looks down for a moment, then looks up again, laughing froggily. "Frog's Theme" starts playing.

Frog: My name is Glenn!
Cyrus's wishes and aspirations,
and this, the Grandleon...
I here and now inherit them,
and will strike down the Magus!

Frog takes the sword by the hilt, and lightning crackles around it. He pulls it out and holds it aloft, and energy surrounds him and flares from the tip. The pyrotechnic display fades, and he waves the sword around. With a crackle of lightning and residual explosions, he slashes down the cliff wall, which slides aside to reveal a cave. Debris falls in the aftermath. Frog gestures dramatically at the cave with the Grandleon, and the party enters.

The internal storyline progression tracking variable is now 0x87.

Frog now wields the Grandleon, which is powerful enough that his attack hurts more than Crono's or Robo's, despite his comparitively low strength. When wearing the Hero Badge, he gets critical hits more often, meaning even more damage on average when not using skills.

"Underground Waterway" plays in the cave, where a bat follows them around, fluttering away whenever there's a battle, then returning afterwards. Magic works better than weapons in here, and some of the monsters are near impossible to kill without it.

The monsters here are the ratlike Greming (Gremlin) and the batlike Vamput (Vamp). The Vamput has low magic defense and normal physical defense, and can drain MP as a counterattack. The Greming has very high physical defense, normal magic defense, and no interesting abilities.

Frog: Could what you're using
be what they call magic?
I heard none could use it
now but the Demons.

Marle or Lucca will respond with this line...

: If we go the Farthest Reaches of Time,
you might become able to use it too.

...and Robo with this one.

Robo: If we go to the Farthest Reaches of Time,
you MAY become able to use it as well.

The party passes through the cave, finding a dead soldier at the far end. It's anyone's guess how he made it in here.

Outside, they find themselves on an island with a large castle deep in a dark forest...

The castle is large and imposing. Bats hang from the twisted trees nearby. Frog steps forward.

2-22 魔王城 (Magus Castle) plays. The bats flutter out of the trees and toward the moon, partially hidden behind a huge gargoyle atop the tallest tower. The bat from the cave is still following Crono.

The internal storyline progression tracking variable is now 0x88, starting the next chapter.

Repairing the Grandleon—which could not possibly have happened in the original timeline given the lack of either materials or artisan—has the potential to be significant, as does motivating Frog, but so far, potential is all there is. No historical impact yet.