My brother-in-law became my sister-in-law, so I'm thinking of making aggressive moves on my sister-in-law.

"Next time, I'll face it properly." Summer of second year of high school. A stepsister created by her father's remarriage. A blonde beautiful girl who graduated early from a prestigious American university at the young age of sixteen. Maria Otsuki. Her stepbrother, Nozomu Otsuki, couldn't accept her and died in an accident. When he awoke, time had rewound to that summer of second year. For some reason, as a woman. Nozomu, who finally accepted Maria at the brink of death and regretted everything up until then, is now determined to live properly as a stepsibling—or rather, stepsister—and tries various ways to look after Maria. But the relationship between him and Maria becomes subtly different than when he was a man... "I can't bear to have my swimsuit seen like this." "Y-yeah, sorry." An oblivious, overcomplicating former boy and a genius, cool-dere blonde beauty girl. A romantic comedy where these two don't quite mesh well together—begins now.