Seoul Special City, South Korea.
The new rising rival to Japan? Progressing their technology, spreading their culture worldwide.
The country of delicious rice cake and the hometown to K-Pop.
Right here, in Myungdong to be precisely, three young, lovely, ambitious men are running a preschool; the preschool of love.

Kim Sunggyu (24): or ahjussi, how the kids keep calling him when they're upset, eventhough he told them not to because he's only 24.
Other than that and what he actually prefers is being called Gyu appa. Although he's the naggy kind and a little strict... and lethargic, the kids love him. Especially when he's singing them to sleep and playing instruments.
Also the owner of the place, which also happens to be his home and living community to his employes (friends).
Being passionate about music, the kindergartner chose to look after kids until he made his mind about the music industry.
Of course, he auditioned and even got accepted but having graduated with top grades, he didn't know whether to do music or choose a steady job. What will his decision be in the future?
Career aside, Kim Sunggyu is the object of desire to his two employes, until now not having noticed it. What will happen when he does?

Nam Woohyun (22): or Nam appa. That one appa that is too greasy and sometimes weird, but the kids still love him like that.
And same as with Gyu appa, they enjoy his voice during the music time.
Being bestfriends with Sunggyu (since their highschool days), both guys share the same interest: music.
He too auditioned and got accepted but couldn't make a decision. Unlike his bestfriend though, Woohyun wasn't making his decision because of love. He wanted to follow Sunggyu's choice. He was having romantic feelings for his friend for a while now, noticing that after one day their touchiness got him butterflies into his stomach. He couldn't think of a future without him, but didn't confess yet either. Kept sending signals that the other still couldn't comprehend.
This not being his only problem, he had competition: his friend Kim Myungsoo. What will Nam Woohyun do?

Kim Myungsoo (21): or Myung appa, the favorite appa of the kids: drowning them in love, gentleness and fun.
Myungsoo wasn't the popular kind of guy, though being more than handsome. He was introverted with others but once he became closer with them, his dorkiness and cuteness overwhelmed them completely. He became friends with Sunggyu and Woohyun in high school and fell for his eldest hyung right away. Trying to keep it a secret for years now... He simply couldn't. Woohyun was fast to find out about his feelings, who himself had the same problem. But because Woohyun and Sunggyu were bestfriends since forever, and were quite touchy with each other, Myungsoo wanted to keep it as a secret too. He was sure Sunggyu would choose Woohyun after all... And being rather sensitive, he didn't want to risk getting rejected by his beloved hyung.
His dedication, beside Kim Sunggyu, was photography. He wanted to become a professional photographer one day, right now still training himself and looking after kids to earn a living.

Lee Howon (22): or Hoya appa. This character is gonna into the preschool and change lives there.
He's a passionate dancer who graduated with not so good grades, looking for a job where he can earn some money for his future dream of being a professional dancer. He got accepted by a company but didn't have the money to join them immediately, so why not working in a preschool and having fun with kids?

others:
the rest of infinite, shinee, miss a and apink
and maybe other cameos too...
(I chose my favorites ^^)