Name of manga i forgot. Had two plots about mc's who look alike.

[Athymababyy]

Hi! I would say the overall genre was sci-fi and mystery (a bit of romance). The main plot had two characters. They where both boys. One had Blonde spike hair and wore a black outfit. The other one was a boy with black hair but switched over to his sister's (?) body who has purple normal length hair and a cool retro jacket. They both fight these wierd monster things and help people by killing them. Their setting is just roaming outside(destroyed city) and meeting people. ( I forgot what they're main goal was) I think the blonde spike hair boy had some kinda power. The other main story is set in this enclosed area that has a bunch of kids(kinda like the promised neverland but they're are some scientists and robots taking care of the kids, possibly doing some sort of experiment?). The main kid is a girl it think and looks very similar to the boys with the blonde spiky hair. I rember at one point one of the kids got very sick and died. The girl also confessed her love to a boy and they slept together I think.

I know this must sound so confusing, but I appreciate any help given!

 

[Athymababyy]

Also excuse my horrible grammar 😓

 

[Yatsuki]

@Athymababyy Is it this one?
https://mangadex.org/title/23535/tengoku-daimakyou

 

[Athymababyy]

@Yatsuki Yes! Yes! Yes!! Thank you so much!!