Frog, also known by his human name as Glenn, is a major character in Chrono Trigger.
Frog is a playable character and the main protagonist of The Middle Ages
Frog and the party defeat the leader of the Manolia Church monsters, Yakra and rescue Leene. Once all three return to the castle. Frog, disgusted that he failed to prevent Yakra's capturing of the Queen, decides to leave the castle for the Cursed Woods. Before leaving, he praises Crono for his swordsmanship.
Frog finds Crono's party in his home. He invites Crono to practice sword fighting, but when asked to aid the fight against the fiendlord, Frog refuses, still believing he isn't a worthy knight.
Crono returns to Frog with the Masamune. Frog debates if he should join the fight and reminisces on past events 10 years ago. The flashbacks show Frog as a human named Glenn. He was a scribe to the valiant, late knight of Sir Cyrus. He assisted Cyrus on his quest to obtain the frog's badge and defeat the The Fiendlord. Cyrus was killed by Magus though, and Frog was cursed by Magus to take the form of a Frog. Returning to the plot, Frog decides to join the party on the quest to defeat Magus.
Frog and the party confront Magus while he is preparing to Summon Lavos. After defeating Lavos, the party finds out from Magus that he did not create Lavos like the party prior thought. The summoning of Lavos proceeds unstably which causes multiple gates to suck the party and Magus to different time periods. Frog stays with the party in the hunt for Magus
The party confronts Magus on the North Cape. Magus curses himself for his weakness while also insulting both Crono and Frog for their alleged foolishness for challenging Lavos. The argument gets heated and nearly erupts into a fight, but Frog decides to spare Magus. Magus then joins the party.
The party explores the Northern Ruins in the Present where they find a grave of a hostile soul. The ghost attacks the party, but Frog quickly realizes that it's the grave of his former master, Cyrus. The ghost disappears.
After the ruins are repaired by the Middle Ages's carpenter, Frog visits Cyrus grave. Frog and Cyrus exchange their true feelings and unfinished thoughts to eachother. Cyrus's soul is finally put at rest. Frog's Masamune also upgrade to the Masamune II. Frog's name was also changed to Glenn from that Episode forward.
- Ever since the end of Episode 43, Emile had a hard time remembering that Frog's name was now Glenn, and not Frog.