honestly i think kojo would both enjoy it to recieve and give chocolate. kojo isn't that big of a sweet tooth, but will forever love chocolate (only mlik chocolate.) He's pretty picky though, and prefers a bar of chocolate rather than some fancy heart shaped stuff or shit that's in colour.
I also dont see him actually giving chocolate on valentines day, but rather act like a sweat and make a basket filled with things other MCs like. He'd put a lot of effort in it, planning weeks, if not months ahead observing and subtly asking questions to figure out what that MC likes. He isn't the person to give EVERY MC something on valentines day, and would probably only give Jude, Fio, Bacon & Kathryne, Leonard, Mari, Runie, Maeve and Haruki. (Maybe Captain Luz's MCs as well but i've yet to read through their lore so idk if they'd get along with kojo ๐)
Yuming would recieve a lot of chocolates and love to give them out, too! She isn't like kojo, and probably wouldn't make a whole gift basket for EVERYONE, but Mari and Fio are DEFINITELY getting them. I don't think she'd give everyone's MCs gifts either, and besides those two, Maeve, Jude, Runie, Kathryne, and Bacon are probably getting chocolate.