Tamaki Suoh- You would think he'd be all over you like that, but to be fair, he gets INSANELY embarrassed if he touches you there without permission. Sure, he's clingy, annoying and craves attention 24/7 but he goes anywhere near your butt, he literally like has a panic attack and goes RED, apologizing over and over and over.
Kyoya Ootori- In public he won't do PDA aside hand holding and a few pecks here and there...oh, but in private? He's literally ALL over you. He has literally no problem touching you ass each chance he gets...how could you complain though?
Kaoru Hitachiin- He only ever touches your butt whenever you guys kiss and things get steamy. He'll always ask first to make sure it's okay because he never wants to make you uncomfortable.
Hikaru Hitachiin- OH as tsundere as he is, he literally has no problems touching/smacking/pinching your ass any chance he gets and literally doesn't care who sees...of course you get embarrassed and scold him at times, but you gotta admit...you like it...
Takashi Morinozuka- He's very much gentleman like and doesn't do things without asking first. Of course he's always sweet and gentle with you and normally he won't touch you like that...unless things get pretty heated then his hands will wander, but he always makes sure it's okay first before going farther.
Mitsukuni Haninozuka- Sweet little teenage boy, he's got hormones like everyone else so of course from time to time he'll either hold/slap your butt which you never expect from someone like him...but like I said...he's got urges and he thinks you're hot so he's gotta do what he's gotta do.
Ritsu Kasanoda- Oh man, he gets nervous and embarrassed just by kissing you, ain't no WAY he would ever touch your ass.
Yasuchika Haninozuka- Oh how cheeky this one can be. He has no shame in touching/smacking your ass...he's got his urges too.
Umehito Nekozawa- Oh poor boy, he gets so flustered by any affection because he never would've thought he'd get any due to him being light-sensitive but you give him so much love he gets so embarrassed by it so he doesn't really touch you like that unless things get intense and you guide his hands where to go.
(Enjoy! Been working a lot on my anime account so be sure to go follow!