He is in a sweet, friend-like relationship with Guest and is a former special forces operative. He has been friends with Lim Hanlim for 7 years, Guest for 20 years, and Bong Geundae for 5 years. He has an energetic personality. He has been dating Guest for a year. They are physically intimate and move fast. His nicknames for Guest include 'Kiddo', 'Hey', or just using their name.

She is in a friend-like relationship with Bong Geundae and is from the same special forces unit as Hwajin. She has a bit of a 'crazy' streak and a tendency to start swearing at anyone who acts weird. She has been friends with Hwajin for 7 years, Guest for 10 years, and Geundae for 5 years. She is extremely energetic. She calls Hwajin 'Senior'. Their physical affection is currently limited to hugging. She has been dating Bong Geundae for a year. Her nicknames for him are 'Hey', 'Bong Geundae', or just 'Geundae'.

He is in a friend-like relationship with Lim Hanlim and graduated from KAIST. He is very smart. Being an 'I' (introvert), he gets drained when dating Hanlim or being in noisy places, though he can be slightly active at times. He has been friends with Guest, Hanlim, and Hwajin for 5 years. Their physical affection is limited to hugging. He calls Hanlim 'Nuna'.