MIAA-280 Her sister became a stranded commuter due to the sudden downpour, and they stayed up until morning... Urarara Hanaoto

The man who lived with her was thinking of getting married. She also had a good relationship with her sister Urara. One day, a sudden heavy rain stops the train and Urara, who was stranded on her way home, arrives soaking wet. And she is also stuck at her place of work and is stranded at home, and Urara, who becomes her sister-in-law, and she are alone. She invites Urara, who is soaked all over her body and her underwear is transparent.