so in the latest manhwa chapter, it's about to be his 21st birthday.
but based on the details in the novel (moondae's ID card / registration, his age difference with real Ryu Gunwoo, the year Gunwoo took CSAT), there is a high possibility that Sejin (along with Moondae and Ahyeon) were born exactly in the year 2000. so this year they're already 25...!!! and is in their 5th year with TeSTAR (so i'm a noona fan.... hahahahah!)
so in the latest manhwa chapter, it's about to be his 21st birthday.
but based on the details in the novel (moondae's ID card / registration, his age difference with real Ryu Gunwoo, the year Gunwoo took CSAT), there is a high possibility that Sejin (along with Moondae and Ahyeon) were born exactly in the year 2000.
so this year they're already 25...!!! and is in their 5th year with TeSTAR
(so i'm a noona fan.... hahahahah!)