- They were all born in South Korea.
- They all have brown eyes.
- All of them go by their real names instead of stage names.
- HeeJin, HyunJin, and YeoJin's characters in the LOONAVERSE all live on earth.
- They all are in the young LOONA.
- They all bleached their hair.
- They were all in the Ssireum team in September 2019 edition of ISAC.
- They all are in LOONA 1/3 
- HeeJin and HyunJin are '00 Liners, but YeoJin is a '02 Liner.
- HyunJin's and YeoJin's zodiac sign is Scorpio, while HeeJin's is Libra.
- YeoJin's representative animal is the only one that's not a mammal.
- YeoJin is the only member to debut in 2017.
- HeeJin's blood type is A, HyunJin's is AB, and YeoJin's is B.
- YeoJin is the only one to not release her solo album in the same month as her birthday.
- HeeJin and HyunJin were trainees together at Polaris, but YeoJin was not.
- Heejin is a lead vocalist of the group while YeoJin and HyunJin aren't.
- HeeJin and HyunJin can play the piano. YeoJin had to give up because her fingers are too short and her hands are too small.
- HeeJin and YeoJin have deep speaking voices, HyunJin doesn't.
- They are in the group LOONA.
- They all dorm together with HaSeul, ViVi, and the ODD EYE CIRCLE members.
- With JinSoul, they make 4Jin.
- 3Jin is sometimes used to refer to HeeJin, HyunJin, and RyuJin of ITZY, whom HeeJin and HyunJin befriended while contestants on MIXNINE.