Yomeiro Choice

"The story is about Saku, a high school student who lives with his cousin Ran and has a childhood friend named Karin. It turns out a girl suddenly appears in his house and claims to be Karin's and Saku's child from 10 years in the future. Not long after, another girl appears and this time she claims to be Ran's and Saku's daughter.
Now both girls are convinced that if Saku doesn't marry their respective mothers they will both disappear, and things aren't turning out easy for him..."