Nymm

Nymm is a bug that moves to Dirtmouth after getting the Banishment ending. He plays an accordion-like bug to bring cheer to the fading town.

He will give the Knight the Carefree Melody charm when he is talked to. (Neither talking to Nymm nor wearing Carefree Melody will give the Banishment achievement, but rather the next time sitting on a bench.)

Trivia

 * It is greatly implied that Nymm has connections to the Grimm Troupe, since he appears after they leave, resembles Brumm and carries an accordion, much like Brumm. Carefree Melody also bears resemblance to the masks wore by the members of the Grimm Troupe. Nymm may be Brumm without any memory of the Grimm Troupe, as dialogue from both Elderbug and Nymm himself suggests that he may have lost his memory.
 * The music Nymm plays, Accordion Nymm, has the same melody as the Dirtmouth theme.