MTL - Rebirth Married The Control Group Fulang - Chapter 6

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

Yukima Azuma—charismatic, confident, and utterly unforgettable. He was the man every girl wanted but could never truly keep. One by one, they fell for him, only to be left with memories they couldn’t erase.Kasumigaoka Utaha: “I was his first, the one who taught him love… only for him to use it on other women.”Sawamura Eriri: “If I hadn’t been such a tsundere, maybe things would have been different.”Yukinoshita Yukino: “He was my light in the darkness, the only one who ever truly saw me.”Yukinoshita Haruno: “That bastard ran away after taking everything from me.”Hoshino Ai: “My only true love. The one I can never replace.”And when asked about their relationship with him?“Ex-girlfriend.”But to the women still in his life?Sora Ginko, Kato Megumi, Sagiri, Bocchi, Shinomiya Kaguya, Kirisu Mafuyu, Suou Yuki, Alya—“Thieving cats.”Because no matter how much time passed, no matter how far he went—one truth remained: Yukima Azuma was the one man they could never forget.

A fluffy, sweet modern GL story about a mature older women and a cute university student.

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.