Some kind of magic power source in an interstellar empire breaks apart into 12 pieces, so the military of that empire finds 6 cute girls throughout various branches and trains them into supersoldiers under the command of a deposed general who needs to regain his honour. During the training they form a close bond and the girls as well as the general are very close, so the general volunteers to go with them. They then set out across the universe in a space ship, to collect all the pieces and restore peace. The girls do their best to overcome the challenges of space and collect the fragments while the general does his best to lead them and care for them. It will be like one of those shounen series that never ends, except this will be moe and fun, and it will have a happy ending where they return home and restore peace, allowing the general to retire in honour someplace in seclusion with all the girls.
I know this is probably a dumb idea because I'm just slapping together my favourite genres of epic magical adventure, cute girls, and harem, but I think it's a really fun idea.