Undertale with Voices Pacifist 19 - Boundless Determination

Long ago, there were two races that went to war with eachother: Humans and Monsters. The humans won of course and after the monsters surrendered, they were sealed underground with a powerful magic barrier. One day, a human known as Chara falls down Mt. Ebott and into the same underground that the monsters lurk in... In which a boy meets an old friend.