Based off of the synopsis both of these have a similar premise of hearing a voice in the rain. Our lead characters are fated together like soulmates.
In Voice in the Rain, our main character Rin is a fashion designer and can hear one voice anytime it rains where she sparks inspiration for her clothing.
In La Pluie, the story follows a character who dislikes strangers and talking to people as well as suffers from sensorineural hearing loss when it rains. However he can only hear one voice during the rain.