I don't see any reason to feel bad for Arata at all. He's the closest thing to a villain in this manga series, without being a bonafide villain. Arata was a poorly-written character whose actions against Yoshinari made Junsuke and Shinobu as side characters for a few chapters.
***Major spoilers for those who haven't read the manga***
Yoshinari had nothing to do with Junsuke's past actions as a host, but Arata saw fit to set Yoshinari up to be r@ped by Junsuke's former clients as his so-called "revenge" for his deceased sister. Yoshinari was looking for work and Arata used that to his advantage. And worst of all, Arata was all like "what's the problem, I picked the right woman for your 'first time' so you should be thankful." Not in those exact words, but still, that's the lowest thing anyone would say after having someone else r@ped, and then going so far as victim blaming by saying Yoshinari is too trusting. And once Yoshinari finally put 2 and 2 together, Arata goes on with his sob-story about his sister, as if doing so justifies his schemes and make him sympathetic, which didn't work on me at all. He could've directly confronted Junsuke, but instead he roped in Yoshinari as a revenge by proxy, and then decided to ditch his revenge plan once he deemed it no longer worth it.
I already typed an entire paragraph about why Arata is unsympathetic, so I'll stop before I und up typing a novel.
yoshinari just pisses me tf off, i feel bad for arata sigh