FUCK YES.
This is the good shit. This is quality ship material and I don't know how it's so underrated because goddamn is it amazing.
They have so many sweet moments together and Shuichi definitely has a crush on him. Literally, one of his lines during I believe their fourth FTE: "I shouldn't be having thoughts like this about another boy". So close to canon it physically hurts. Not to mention their Love Hotel scene is one of the few that's genuinely sweet instead of being weird and creepy - and the only one Shuichi really gets into. Even with Kaede's he's a little awkward and hesitant, but during Kaito's he's way more into it than someone just playing the part would be.
And yes, I am aware Kaito called somebody a f***** in the Japanese version of the game, but since Kaito is my favorite character and I am desperate not to have him ruined for me I'm just going to remain in denial of that fact. It's not in the American version of the game, so I'll just bury it real deep and pretend it doesn't exist, like all my problems. Plus, I'm not sure if that would make any gay ships with him inherently 'toxic'. If anything it would add an additional, interesting layer, like Kaito's got this internalized homophobia and calls other people gay because he's so insecure about being gay himself or something. I don't know, just something to think about.
Anyway, back to the ship. It's perfect. It's literally perfect. It's the perfect ship. Depressed emo boy x overenthusiastic idiot? The ultimate ship dynamic. The two of them really care about each other, they're both great characters on their own with Kaito being my all time favorite (literally, I've made a list of every single character in this entire fucking franchise excluding some of the add-on light novels I haven't read, and Kaito is #1) and Shuichi placing in the top 20 at least, and all of their interactions are pure fluff. I don't understand how this is so underrated. Like, I get if you just see them as friends, but come on, I can't be the only one who wants them to get together.
I have to give this a 10/10. One of the few perfect ships in the known universe. Beautiful beyond compare.