Minato Sahashi remain as a gentleman. He could have sex with his Sekirei harem if he wanted to as long as they really wanted to do it with him out of their own free will. I know he'll be gentle with them. Sekirei would be a nice, sweet, vanilla hentai with the harem plot and without any censorship. The reason why this Sekirei series is prevented from become 18+ because of their landlady Miya. She states that illicit sexual relation is strictly forbidden.
Minato's virginity would have been lost to Musubi, and/or Matsu if it wasn't for Miya. What do you expect?