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My sister, my wife, my dearest love - I will hold you in my arms until you are impregnated...

In the early Taisho era (1912-1926), while her friends at the girls' school were getting married one after another, Yo Tachibana was also dreaming of marrying a wonderful man.
Hikaru, Yo's older brother and a second lieutenant in the army, is called the "ice officer" because of his cool personality and outstanding appearance, and is the object of admiration among the female students.
However, for Yo, the mean and overprotective Hikaru was a bit of an unwelcome presence.
One day, her father tells her that Yo actually has a fiancée.
Yo is excited by the sudden mention of a relationship, but turns out to be Hikari...!?
"Cute, cute...my sun..."

My sadistic stepbrother's love for me won't stop!
Taisho love romance!