Looking for a manga, which I'm sure someone will know.

A bolt of lightning strikes in front of the main character and a random guy appears. He is from the near future and eventually has to go back.

He gets pulled back after a while and the main character is all despairing and such.

But then it turns out that when the guy returns to his own time, his most admired person is actually the future version of the main character.

maybe Itsuka Koi ga Kanau Made .. but I'm not sure...

Yup that's it thanks 🙂