Todaaaaay is my Bleach fave's birthday!! Which has, despite him being a relatively minor character and it not being a series overly concerned with birthdays, been repeatedly mentioned in canon. I think part of it's because of the non-human characters, Hitsugaya is the only one still within or near an age reminiscent of the human lifespan. He's still a child. And while his birthday or its celebration almost certainly does not feel that important to him, I think a lot of the people who care about him still think it's special, and want him to have some piece of a childhood he'll never have.
Cup: Vaguely elemental sea glass design, because he seems to like that color, and he has ice- and weather-type abilities.
Tea: Lion's Mane mushroom "elixer," because his given name is Toushirou (冬獅郎), which uses the characters for "winter" and "lion." (His sword spirit is a Chinese dragon, but let's be honest, Chinese dragons and lions honestly look kind of the same). And his family name is Hitsugaya (日番谷), which is a locational name that basically translates to the valley where the mountain blocks the sun, a place I associate with mushroom hunting.
Snack: Kabocha amanattou steamed buns, because his favorite food is amanattou (which are candied beans, an old-timey snack most commonly associated with old people), and kabocha is a winter squash. Plus it's such a bright color, I feel like Hinamori (his closest friend/foster sister) would want to gift him something bright. 😊
Thank you for 13 years of knowing you! I still love you. ♥