oooo hmm It definitely varies depending on what they're interested in at the time but...
Kuma usually gives Tahi some sort of romance novel or manga that he hasn't read but he also tries to make sure it's something they'd really like (cute and lighthearted, some drama's okay, but absolutely nothing raunchy cause they get extremely overwhelmed and flustered otherwise.) which means he also has to read/skim through them himself even if he hates to do it. (mostly due to past romantic experiences but he also finds most of the stories he's read to be really cheesy barring some that he surprisingly ended up liking.) Sometimes he'd get Tahi a new bartending set for work, or a cookbook that they were eyeing on, or even a big plushie and if he could afford it at the time, some nice fancy tea from the local tea shop near their apartment. He also treats Tahi to a big sundae(s) on their birthday!
Tahi on the other hand likes to go all out and surprise Kuma with a big ol' cake on his birthday either homemade or if they don't have time(or rarely, if the cake gets ruined...) they get one commissioned from a local bakery (usually the firbolg bakery unless kuma's working there at the time.) They know how much Kuma likes shiny objects and trinkets so they usually get him an assortment of things like a jar full of sparkly beads (kinda like the ones that hang from kuma's collar), a few jewelry pieces like bracelets and a cherry blossom necklace, and glittery star sand in a bottle. One time for starlight season (~coughs wildly~ christmas!!!) Tahi got Kuma a star shaped brooch with a star sapphire in the middle of it.
It intimidates them slightly, but Tahi occasionally tries to get some sort of magic item or temporary enchantment for Kuma too. like a stone that lets you float all day, or a potion to make you taller (or shorter) for a small amount of time or even just a spellbook if they aren't sure what to get. There's also a ring they got that lets you do little things like shoot out bubbles and sparkles or light a candle (pretty much a limited-use dnd prestidigitation) It didn't last all that long but it still made Kuma really happy regardless.