About the fact that only my **** can bring some sense to a stupid little sister / Baka na Imouto (4 episodes)

Our hero, a lonely loner, but soon everything changes, the dullness and ordinariness disappear somewhere. In the center of attention is a new heroine, "who is she?", "Why does she have such a beautiful voice?" - our former hero keeps asking himself this question...

 

Mitsui Yuichi is the most ordinary student. He moved out of his parents' house to enter university and now lives alone.
He doesn't have a girlfriend... because he's crazy about his little sister.
"If this continues, I'll cross the forbidden line" - these thoughts made Yuichi reluctantly choose a university far from home to keep his distance from his little sister.
However, one fine day during summer vacation, his beloved little sister appears at the doorstep of Yuichi's apartment.
After two years, his little sister not only remained as cute but also gained a full bust, a wasp waist, and a firm butt.
Hana - that's the name of the owner of this body of unearthly beauty. But she has one significant flaw.
And this flaw is that... she is incredibly stupid.
Just three steps and she has completely forgotten everything she learned. She can't read most of the characters, and she can't use a remote control with more than three buttons at all.
Yuichi decides to embark on a thorny path, just to teach his sister some sense, who otherwise has no way into normal society.