Go Crazy! the Aloof Senior Has Been Secretly in Love with Me for Seven Years

After seven years of traveling through time, he entered into a contract marriage with his aloof senior sister. After marriage, they respected each other like "ice". I thought we were disgusted with each other until I pried open her secret attic - [Warning: You have been secretly in love for seven years]! It turns out that what she wrote was not an experiment report, but a love letter to me!