Only Kiss Without Love (2018)

Xiao Bai Yu is the CEO of the Feng Sheng Department store. He is the illegitimate younger grandson of the Xiao family. He was made CEO when his elder half-brother Xiao Jun Jiang had an accident and Jun Jiang resents Bai Yu for this. Tong Tong is a reporter who inherited a strange disease from her father – once she kisses a mammal, she becomes a man within three minutes. One day, in order to change back to a woman, Tong Tong kisses Xiao Bai Yu in her male form, which starts rumours that Bai Yu is gay. To dispel the rumours, Bai Yu asks Tong Tong to pretend to be his girlfriend.

Both Chinese dramas are about a person who changes sex on kissing. In rules of love, Luo Tian who has identified himself as a boy becomes a girl on kissing the ML while in Only Kiss without love, female Tong Tong becomes a man on kissing a mammal.

Its slightly the same .
The female lead in the beauty inside changes to a different body and new identity for one week a month while the female lead in only kiss without love changes whenever she is kissed by any mammal.but the similarity is the change of bodies in both series
Both dramas are dealing with contract relationships
Both dramas have rich male leads.

The similarities are
rich famous male lead
Hate to love relationship
Tsundere personality of male lead
A Scene where leads are lost in a snowy place