i also think kenma isn't that interested at first, like you said with iwa, but he probably has a keychain of a character from his favorite game or a little plush of a cat hanging from his bag just because, "it's cute" he tells you. but he'd follow you willingly when you want to stop by the kawaii shop and he'd look at all the keychains and plushies and standees with you, he'd think and you could see the gears turning in his head, and in the end, when you've decided what you wanted to leave with, he collects the ones you couldn't choose and he'd hand the cashier his card, ignoring your protests. i think he'd enable a little bit, not too much where it's beyond reason, but just enough to spoil you and get the things you want and you wouldn't leave with regret. he'd collect all the reward points and he'd keep up with all the updates of your favorite gacha games and the collabs that they may have, because he has the time to and why not? it's kinda fun. he'd stand in line for hours with you, trying again at a level he couldn't beat the night prior, wave you off when you try to apologize for the nth time. he'd help you take all the pictures you want because maybe you want to upload them onto some sns. he's surprised himself when he blinks and his room had transformed, with display cases and various figurines of characters you'd barely managed to convince him to buy (he was more interested in what you wanted). he has multiple going-out bags now, aside from his trusty black messenger, each with their own keychain and each with their own memories.
he wasn't all that interested before, but it's fun, so it brings a little bit more of a smile to his face :3
