Baituo, Wo Zhen Mei Xiang He Zhangmen Tan Lian'ai A

Li Ran traversed to another world and became the scion of a demonic sect. When his system awakened, the first mission it gave him is to romance a girl? Li Ran was going to seduce the cute and gullible junior girl, but he ended up sending his love letter to the Master of the sect instead! That woman is a ruthless, cold-blooded, killer! As Li Ran was considering what he's going to do in his next life, he finds out that the master is actually… "very nice!" (Source: Bilibili, translated)