Honkai Impact: Dreams and the Holy Grail, but the Servant is Rei.

Plunged into the universe of Honkai and Iron, Meng Weiyu strikes a high-stakes wager with the Lord of Pleasure: conquer a brand-new, unauthorized mini-game known as "Dreams and the Holy Grail," and earn his long-awaited ticket home. With the chaotic "assistance" of Aha, he steps into the summoning circle, sacrificing his own flesh, blood, and memories as catalysts to summon a legendary figure from the Honkai Impact 3rd universe as his Servant. As the magical incantation peaks, a familiar pink-haired girl in a purple dress begins to materialize. Yet, at the final, fragile second, fate twists. The crimson tip of a spear presses coldly against the young man’s brow, and this time, no one steps forward to protect him. Armed with a transmigrator's ultimate survival tool—the newly awakened "Performer's Encyclopedia"—Meng Weiyu must defy the odds. Alongside an unconventional Caster, he embarks on a desperate rebellion to rewrite a predetermined destiny and find his way back home.