Kaoru's father was a Yakuza
His mother rhapsodises about how he was "a real man's man! So strong and vicious!" Since he's dead, I assume he was in something dangerous. And it worked for Toradora!
Yukari and the Prez will get together in the end
She's crushing on him and apparently finds the idea of collars exciting. He wants to be dominated by a woman who seems strict but is actually very cute. Hm.