ＨＳＫ ～Ｈな妹とツンな幼馴染に挟まれＡＤＶ～

"Stuck between Imouto and Osananajimi..."

For our protagonist Souichi it is a daily routine to get raised by his Imouto Hadzuki, and than go to school with her and his Osananajimi Kotone.

Someday, his parents suddenly had to go on a business trip for half a year.
While Hadzuki was made to go shopping, his parents told him that she is infact not his real Imouto -- that they don't have any connection by blood.

Hadzuki was secretly peeking at this scene.

After she learned that there is no blood-connection between them, she approched her beloved brother.

Kotone noticed that, and in order to keep Souichi's desire away from his little sister, she had sex with him...

And thus his H-days began -- stuck between his proactive-perverted Imouto, and his Osananajimi, wich tried to keep them from doing "it".