He was at Hogwarts, and had just become a Half-Blood Prince.

[Parent-generation; multiple female protagonists; no system]

…

In 1976, 16-year-old Severus Snape welcomed a new life.

That year, Voldemort had not yet split his soul into seven pieces.

That year, Nagini was still hiding in the forests of Albania.

That year, Pandora was still doing wonderful experiments at Hogwarts.

That year, Ms. Rosmerta was in her prime and very graceful.

That year, Snape decided to experience this wonderful world.

This book is also known as "Come to Hogwarts to Learn to Slay Gods" and "Chainsword + Boltgun: Times Have Changed, Wizard Master!"

In the dark 41st millennium, Bourne faced the Primarch Angron, who had ascended to the devil, in the Warp and was hit head-on by the Spinebreaker.

But his soul was neither polluted and assimilated by the Warp, nor did he return to the Golden Throne.

Bourne came to the world of Harry Potter.

ps: The content of this book is also friendly to readers who don't know Warhammer and Harry Potter. You can rest assured that the protagonist will not be tragic.