Nichiyoubi Wa Issho Ni summary:

This is the story of three girls who all realize that the boys they've been chasing aren't available at the same time, and so decide to meet on a Sunday to invite the first boys they see to a party they're going to put together. Of course, it's not anywhere near that simple, and the three boys/men they pick up are all connected although none of them are aware of it, and some events in their own lives are going to complicate things...