I dunno if you just started to read this. But it was actually Shingo who seduced keechi. Due to the catnip he straddled over keeichi. And he was already interested so..rhey ended up doing it together. There is a backstory of what happened so you'll realize it eventually. Haizz I'm not into rape but definitely there is no rape rhere
I'm currently rereading it, I'm talking about him putting silvervine in the wine causing Shingo to pass out and wake up to Kagami inside him already. Even if Shingo straddled him as you say, he still drugged Shingo in the first place and can't consent when intoxicated. So I wouldn't count that as seducing.
Something I don't understand is why Kagami went through the effort of chasing and raping Shingo when they first met cuz he even said it was just a fling to him. I get that now he's madly in love yadda yadda and that it's a common troupe in yaoi for rape equals love which is dumb but idk I found the start of their relationship hella weird. I just don't understand why y'know?