Assuming that Imai is referring to himself, he is probably Ishikawa's uncle, not his grandpa. If it's a FF5 reference (and refers to a certain event I haven't reached yet myself in the game), it makes sense why he would call himself "grandpa" instead (well, kinda).
That! That is MY line!! Self-Destruct
Imai
Ishikawa
Imai
Imai
DIE!! FLARE
Mori! Fall in love and be a bit more womanly, now.
Chakapi/Calimero
.... Uncle... Not sure why, but Ishikawa definitely uses "Uncle" instead of "Grandpa".Okamura! Never forget that kindness to sympathize with animals.Kenta! Just once...I'd wanted to challenge you one on one! You've been a good friend..... Imai...IMAAAAAAAIIIIIIIIIII!!!!!!