If you're looking for anime similar to Boku wa Imouto ni Koi wo Suru, you might like these titles. All recommendations are made by Anime-Planet users like you!
Once upon a time, two brothers passed the happy days of their childhood by studying alchemy, which is governed by the equal transfer principle: an eye for an eye -- you can't get more than you give. But these brothers tried to defy that law, and a horrific accident resulted. Now, the older brother, Edward, is called the Full Metal Alchemist because of his metal limbs, and the younger, Alphonse, is a soul without a body, trapped within the confines of an automaton. Together they search for the power to restore themselves, to find the lives they lost so long ago...
These stories don't have much in common at the first sight, but if you look closely, you'll see it. Both series are primarily focused on the strong bond between siblings. And also in both series the siblings committed taboo. You can see complicated but different relationships and specific problems main characters try to solve. Both stories are deeply touching and make you think of something you perhaps have never thought of.
Kyousuke Kosaka is a normal teenager with average grades and an average home life, but when he finds out that his overachieving younger sister Kirino has been hiding her vast anime and eroge collection from their unassuming parents, his world turns inside out! Now, having promised to help his formerly distant sibling navigate her two distinct lives, Kyousuke finds himself drawn into Kirino's world of magical girl anime and "little sister" fetish games while covering for his sibling to her parents and friends, not to mention trying to provide what guidance he can.
Narumi Takayuki is a normal high school student with a crush on Mitsuki, the school's swim star -- that is, until he receives a profession of love from his friend Haruka. But amidst the beautiful budding relationship, tragedy strikes when an accident occurs, turning Narumi’s life upside-down. Kimi ga Nozomu Eien is a compelling drama about one man, and the choices he must make for love.
Both of these animes share a few key similarities: Forbidden love, a very adult feel and bittersweet sorrow throughout. These two animes made me feel more raw emotion than any of the other's I've seen. Both of them feature a male lead who has to be more manly than he wants to be, choosing what is right over what he wants with his whole heart. Though BokuImou is far shorter, it almost needs to be, as the entire episode from end to end has no light hearted filler, which Kimi ga Nozomu Eien managed to do for the whole season. They also have no fanservive with no ecchi to be found, which adds even more to the heartfelt feelings in them. Both of these have a unique feeling where at the end, you find it very difficult to move on to the next show. BokuImou won't have you sobbing like Nozomu does, but if you like one be sure to check out the other.