At the May 8 press conference for new MBC drama 'Monarch - Owner of the Mask', Yoo Seung Ho was asked about working with Kim So Hyun. 

He commented, "I worked with Kim So Hyun on the same production once when I was younger but we never ran into each other. We never really worked together but I was able to understand Kim So Hyun as I'm a person who also has experience working as a child actor, and I felt like I've known her for a long time."

Yoo Seung Ho then revealed, "Kim So Hyun is 6 years younger than me but I wasn't able to drop the honorifics when we first met. In a way, she's like a noona and she's very mature."

SEE ALSO: Park Bo Gum reveals why he was disappointed by fellow 'When Life Gives You Tangerines' actor Lee Jun Young

Everyone at the press conference including Kim So Hyun laughed at his comment. Yoo Seung Ho quickly responded, "Sorry, I just meant that she seemed very mature when we talked. I'm the oppa but it just felt that when we were filming too... Anyway, it's nice working with her. It's an honor and I'm happy to be working together with Kim So Hyun."

The first episode of 'Monarch - Owner of the Mask' is airing May 10.