Onii-chan, Asa made Zutto Gyutte Shite!

The protagonist, an older brother to four sisters, suffered from severe asthma as a child. As a result, it became a daily routine for him to sleep with one of his sisters. One day, his parents, who are also researchers, ordered him to participate in an experiment to prove the "immune-boosting effects of hugging." "Hug your sister lovingly for at least 10 seconds every day before bed ♪" Now, our protagonist must incorporate this nightly embrace into his routine with whichever sister he's sharing a room in the evening....