My Only 12%

Cake and Seeiw have been friends as far as they can remember. Cake is very outgoing and has a lot of friends while Seeiw is very shy and barely speaks to people he's not used to being around.
Despite their different personalities, they are very close. By being next-door neighbors since they were born, they became an essential aspect of each other's lives. However, as they become older, things change and so do the way they see each other.
There is only a 12% possibility of having a successful first love. Would that 12% be enough?
~~ Adapted from the novel “12%” by afterday.