Falling in love with Bunny is a mistake for more reasons than Kotetsu can list, and he knows about mistakes. He's been making them regularly for most of his life, and at least a solid half of them got recorded and broadcast on live television.
And like all the other mistakes, no matter how good his intentions or how much he knows he shouldn't, he goes ahead and does it anyway.
Tiger & Bunny, Kotetsu/Barnaby, Mistake
And like all the other mistakes, no matter how good his intentions or how much he knows he shouldn't, he goes ahead and does it anyway.