This was for an informal request, I have never watched JJK and only did some cursory research for the sake of the model.
You will probably need to use Adetailer and be a bit lucky to get the eyes right, that was the biggest pain when training and testing this model.
Basic prompt: kirara_jjk, spiked_choker, symbol-shaped_pupils, mutlicolored_eyes, lip_piercing
Main outfit: bracelet, off_shoulder_cropped_sweater, black_pants, red_straps, , multiple_belts, star_belt_buckle, lowleg_pants
Side note: I do take informal requests(basically a bounty that you don't have to pony up buzz for) if I like the idea(Tips are nice but not required since if it's a good idea then I'll get generation Buzz). Just leave a comment on one of my models or DM me. (Comments are preferred since that let's other people see that I'm actually fulfilling informal requests.) DMs are perfectly acceptable if your request is a bit out there and needs some image examples or something. As a note I will probably pass on Manhwa characters because I generally find their designs to be kind of bland.(No shade to Manhwa creators, I know many of them are going for regular releases and intricate designs are not what you want in the case.)