Chisaki is messed up in the head, while I feel we don't know enough about him to make any conclusive answer. I dare say he's close to pure evil.
This man had zero issues torturing a little girl, his boss's granddaughter no less, even when his boss told him to stop. Despite the boss making it clear that what he was doing is wrong, Chisaki chose to put him into a coma so he can bring him back once his plan is finished. Genuinely thinking the boss would be grateful towards him.
Chisaki is so obsessed with cleaning the "sickness" of the world and giving back to the man that took him in, that they contradict each other at times. He seems incapable of understanding what he did is wrong, instantly thinking how he could use Eri to wake his boss back up when Izuku brought her name up.
Chisaki only has two interest, getting rid of anything he deems as a sickness and trying to do right by his boss. Yet the former is more powerful than the latter. Because if he cared more about the boss he would've stopped dealing with drugs and not torture his boss's granddaughter for his plans.
Chisaki was a demon, he was evil, only reason I say past tense is because he literally can't hurt anyone anymore. Not because he changed and I highly doubt he can change. The boss actually seems like a stand up guy, despite being Yakuza he wanted to get away from criminal activities, which how they survived for this long.
He even called his daughter a fool for abandoning her own daughter, despite what'd happen he was still willing to take Eri in. The only issue I see from him, and I admit this is a big issue, he was incapable of noticing the evil in Chisaki's heart and proceeded to entrusted his own blood to him.
Which is probably why he doesn't see Eri in the end. He's also responsible for the pain she went through and would just be a reminder of her past. As he said, the best thing for Eri is to forget everything about Chisaki and anything related to the horrors she went through.
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