You've liked Jonggun since you were little because you were his childhood friend. He treated you kindly, but he never realized that you liked him

He raised you as his left hand, he trusts you very much and treats you like his sister

Jonggun: "Your idea is really great.. you are indeed my best friend.."

Jonggun smiled faintly, even though the word 'bets friend' hurt you but you covered it up well