He does dislike peoplewho use violence to get what they want and has no problem picking a fight with them if they go too far.
Riku is first introduced in Second Year Volume 1 walking up to Kiyotaka Ayanokoji with Sakurako Tsubaki asking Kiyotaka if he would partner up with Tsubaki because she had a C- in her OAA and was in risk not finding a partner up until now. Kiyotaka ended up refusing their offer saying that he already had a potential partner in mind. Tsubaki and Riku accepted that and left