1 needed to calculate an average
Both manga feature a love triangle and a a slightly odd high school club and because of that they are somewhat similar. Unfortunately Ume Shigure got axed before things even started to develop. If you liked one of those two manga and want to read something similar you could try reading the other one.
P.S. Ume Shigure, unlike Sora no Manimani, is slightly ecchi, but not all that much.