He didn't make a Gongjindan (拱辰丹), he made a Gongjindan (攻進丹).*

Like the person who developed Viagra while trying to make heart medicine, Moon Youngha tried to make the ordinary Gongjindan (拱辰丹) but ended up making Gongjindan (攻進丹), which turns people into Alphas. And after eating that Gongjindan (攻進丹), Jung Pureum collapsed on the day of his college entrance exam, even during the English listening test, and manifested as an Alpha.

"Hyung, you have to take responsibility for me..."

Moon Youngha wants to revive his traditional Korean medicine clinic, which is empty because the director is an Omega, and Jung Pureum, the physical education student next door, who has had a crush on Moon Youngha for over 10 years.

"Alright, I'll take responsibility. Stop crying."

In the end, to avoid being sued by Jung Pureum, Moon Youngha blurts out that he'll take responsibility for him...

Note: It's wordplay on the traditional herbal medicine Gongjindan (拱辰丹), replacing a Hanja character to turn it into Gongjindan (攻進丹), which literally means "Advancing Seme Pill," to suggest that the medicine makes someone an Alpha.

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