I started reading this story based on the summary and genre (there was tragedy, which is a lie for the most part of the manga). Wish I didn't do it.
As already noted, the story is really dragged, filled with shounen-level ecchi. The main guy, Shinpei, just doesn't make any sense. "Although I know we both love each other and suffering, I won't touch this girl because we had been living together as step-siblings for 5 years." What?!
The story is choppy sometimes. It cuts in unexpected moments, which left me really confused. Speaking on confusion the last volume just doesn't make sense.
Akane says, "Mother, I can't live with you, sorry." Yet, she leaves for Milan. WHAT?! WHY?! Also, the ending wasn't rushed for the most part, but mere five pages to show them in three years are clearly not enough.
All in all, it's a run-of-the-mill romcom manga. I wouldn't say it's a harem, because there's no more than two girls in one moment who fall for Shinpei. Anyway, don't waste your time.