Daisaku

Background
Daisaku was a Saga Empire's hero predating Hayato Masaki and said to have died 400 years ago, before Satou is summoned into the world, living out the rest of his days in Bolenan Forest. He's credited for making Bolenan's 'genuine elf town' that is used to entertain guests.

Possibly is Lulu's grandfather (13-33) so his last name could it be Watari