Samurai wife!!! Kubo will ply her with sad tales of how he only got to learn Samurai things from his Samurai dad for about two days of his life, looking for fresh Samurai lore. I can't say I can figure out if there's a specific time period his canon is going for, unfortunately!

I am a thousand percent super enthusiastic for Donatello too. TMNT is the crossover I most want to see with Kubo and the Two Strings. Hell I'm super enthusiastic for them all. Kubo doesn't have friends his age in canon due to having excessive responsibility for a teenager, so it'll be really nice to see him meet some equally responsible hero buddies.