>>1918214There are 3 different scenarios in which Yuu and Koharu have "sex" in tachibana (manga/novel).
1. Bathroom scene in the manga
2. Bathroom scene in the novel
3. sex at the inn (before the NTR)
In all three of these scenarios, Yuu is physically unable to penetrate her hymen, but is still intentionally trying to have sex and make her feel as much pleasure as possible. (unfortunately he was terrible at it)
It's hard to really speak to Basara's intentions when it comes to "hymen sex" with Chisato. Considering he spent nearly a year trying to find her pleasure spot i think it's safe to say they moved far beyond the realm of foreplay.
Maybe it's the result of the Master Servant Contract, but I like to think of Basara as a possessive person. He tends to go a bit over the edge when his harem or Mio's purity is threatened.
Up until vol 8 he's had this secret sexual relationship with Chisato that has gone undefined. I don't know whether or not it's lust or genuine love.
I think Chisato openly accepting Basara's raw dick was an act of submission. Him cumming inside was more or less him marking her as his woman. Thus their relationship being defined not only as master and servant, but also as man and woman.
I could totally be grasping at straws, but yeah they have sex, but they don't have "deep" (impregnate me now) sex.