Issei Hyoudou is reborn as a devil servant to the beautiful Rias Gremory. He must climb the demonic social ladder while protecting his new master from fallen angels.
Why it's similar: This is the most direct parallel, featuring a high school setting where the protagonist enters a supernatural contract with a powerful female devil. Both shows balance heavy ecchi elements with a surprisingly deep lore involving biblical mythology and demonic hierarchy.
Power comparison: Both use a ranking system for devils and rely on spiritual contracts that grant the protagonist unique, evolving artifacts like the Boosted Gear.
Why watch after The Testament of Sister New Devil: If you want the exact same vibe with even more seasons and expanded world-building, this is your next stop.