“Big bro… please, stop... let me out of here…”

This is a twisted tale of love between a brother and sister...
The protagonist and his sister Nozomi are siblings, four years apart.
They were incredibly close and spent a happy, peaceful childhood with their parents.
But as Nozomi transitioned from child to woman, the protagonist could no longer see her just as his little sister.
Without the ability to convey those feelings, their sibling bond began to strain,
and as their parents argued over educational approaches, the once happy family slowly fell apart.
Then, during her third year of middle school, a pivotal event came about.
Learning that Nozomi got her first boyfriend sent him into a spiral of jealousy, and he broke them apart.
At this point, he became painfully aware of his feelings for Nozomi—
not the love of an older brother, but a man’s longing.
This awareness deepened the rift between them and after their parents divorced, the family came apart at the seams.
He fled his hometown for Tokyo University instead of attending a local college, running away from the painful memories.
Fast forward four years... approaching graduation, he had all but forgotten about his sister and family, floating through life with no aim in sight.
However, fate was quick to snatch away that calm routine that he got used to.
What a surprise! He accidentally ran into Nozomi in the middle of the city!
As they talked, she mentioned she had come to Tokyo to look for a job. In that moment, the protagonist's long-buried feelings could not be contained any longer!
He slip a sleeping pill into Nozomi's drink and, while she was unconscious, locked her up in his room. As Nozomi struggled to understand her situation, the protagonist whispered in a low voice to her...

— This time, I will protect you, little sister.
— Forever… yes, I will protect you forever.

Thus begins an eccentric story of their “breeding co-living”——

[Translated from the dlsite]