SEE ALSO: Girls' Generation release a preview of their first official lightstick!

Hoon tweeted, "My friend and classmate Seohyun invited me to her musical 'The Moon that Embraces the Sun' today~~~ keke 'The Moon that Embraces the Sun' is so much fun~~hehe Seohyun ah, you are the best!! ke," along with a photo with Seohyun.

Hoon put his arm around her, and they both gave their thumbs up. The two are both theater majors at Dongguk University, so it was nice for the classmates to show their support for each other outside of the school and stage.

Seohyun's musical will run until the 23rd at the Seoul Arts Center - CJ Towol Theater.