☆ʀɪᴅᴅʟᴇ☆

Not every ship is cannon, people know this. A lot of the times, fandom ships aren't even fully implied in the show itself—unless that fan is specifically looking for pairing. If you watch TBHK, almost everyone in the main cast gets some kind of canon love interest. Nene and Hanoko, Aoi and Akane, Sakura and Natsuhiko. But when you see Kou, he doesn't ever fall in love with someone, and his main person is Mitsuba. Because of how the other love stories are laid out, it's very easy to assume that—yes, Mitsuba is his implied love interest / crush. It's only strenthened by the fact some other pairings are heavily implied or shown but never actually date.

Mitsuba and Kou are in a shit ton of official art with each other, exactly how the other couples are. They aren't a ship that people looked and said "oh gay, it's canon now cause I think they should be and cause it's gay." They have an actual story together just like every other couple, except they don't get the privilege of being together nor get to have romance heavier moments like them. That doesn't deny their bond an yearning in anyway