nyanyan00's manga / #ch.6(145)

female lead has 3 older brothers. eldest went missing inside a rift. he came back after many years later. he acts like he has chuunibiyou but he really does have evil powers. It seems like he was the demon king or lord in the past?(or is it future? lol) the second brother just recently regressed. 20 years later, stronger monsters start coming out of the rifts and the humans aren't able to fight against them. Also, the demon lord (who is actually the eldest brother) descends on earth. In the future, he becomes the hero who saves the world and brings peace by killing the demon lord. the third brother is under a coma right now.