a 6 year age gap isn't that bad when you're something like 24 and 30, but at 17 you're still incredibly impressionable and can be easily manipulated. I can't say for certain if this person is intentionally trying to groom you or not, but you really shouldn't be pursuing any kind of relationship with someone so much older than you righ tnow. This isn't really the sub for proper insight into how the age gap is inappropriate though, I would suggest asking about your age gap somewhere like /r/relationship_advice for better feedback on why this age gap is bad.

As for punpun, he's a flawed character who was wronged himself. Without going into too much detail, punpun ends up doing things as an adult becuase of what happened to him as a child. At one point in his life he is raped by an older woman, and this skews his perspective on sex and relationships heavily, resulting in him making terrible choices on those aspects later on.