I'm in Detective Conan, and the system has assigned me a succubus.

To be honest, Toru Uesugi considers himself a normal person.
But the system insists that he is a succubus?
And you need to gradually train him into a qualified succubus. At the same time, you can get rewards by increasing the favorability of the corresponding character.
As Uesugi Tetsu faces increasingly complex interpersonal relationships, everyone discovers that the people they like are remarkably similar.
Vermouth then pressed the gun to Toru Uesugi's forehead first: "You said I was your only one."
"Yes, darling, I did say that."
Shiho Miyano followed closely behind, holding a red and white capsule in her hand: "You also said that I am your favorite."
"Yes, honey, that's true too."
The invincible legal queen, holding the verdict, said: "You also said that I was the most special person in your life."
"Yes, sweetheart, I have never lied to you."
The witch from the Red Magic family watched this scene with a smile: "You also said that I was your destined one."
"Excuse me, Miss Witch, you said that."
...
"So, are you even human anymore?"
"This... needs further verification."