[Mikokuno Homare] Osananajimi

This was nice

As to explain the 'NTR' part in this book: the final two stories. Let's, for short, we have 4 people: A (blond hair guy), B (pony-tailed girl), C (black-haired guy) and D (tomboy girl). A and B are childhood friend, and B and C are childhood friend, on an individual basis. (Aka A do not know C) A loves B, and B loves A. A and B dates. C secretly love B, B also loves C. D likes C a lot. D catches C peeping on A + B => D 'coerce' C into dating her. C still likes B a lot, so asks A and B to have sex, to relieve his crush. Agreed. B and C have sex. C confesses to B. D and A jealous. Still, B loves A more, thus she declined C. Much to A and D's reliefs. A returns to B, and C to D. In conclusion, not so much NTR but... partner-swapping. Doesn't leave a terrible taste after reading it, doesn't feel (too) sad. So... Yeah. Almost vanilla? They can even be seen later on in the omake fooling together!

This isn't NTR, the couple gets back together shortly (they could be seen fooling around with a vibrator, of all things, in the omake.) That and it's more like a bunch of childhood friends swapping around.