they are cousins. a very close cousin. 

kyungsoo's mom decided to move to Japan. they still meets once a month when jongin's family went to Japan and when kyungsoo's family visited their home town. but usually, kyungsoo's family that always visited their hometown since kyungsoo's grandparents were still there.

that once a month meeting last for only two years. kyungsoo's parents became very busy with their company in Japan since it had been expanded to 3 other countries.

kyungsoo misses korea so much. not as much as he misses his cousin, jongin. their last encounter was 3 years back. that was when jongin and his family went to Japan for some business trip. they met for only few minutes.

during his holiday in korea, he had to stay at his uncle's  -which is jongin's father- house since his grandparents died two years back. the reason why kyungsoo wanted to be in korea was all because of jongin. he wanted to catch all the childhood moments with jongin again. and maybe confess his feelings towards jongin.

but then everyday, jongin wont even spare a glance towards kyungsoo which hurts him so much. he was to scared to talk to jongin. awkward actually. everyday, he wont see jongin spent his day in the house. in the morning, jongin will be picked up by some of his friends and will return home after kyungsoo is in bed. why? dont ask why couse he also dont know why. 

EDITED AND WILL UPDATE IN FEW DAYS