It would be about the time for Yoonsung's helper's reasons to be explained. I wouldn't go as far as to call her deus ex machina, but when you have a poor juvenile bullying victim (and now criminal) seeking personal revenge, why does he receive help from a competent adult?
Another mild problem with this arc is how all these troubles (for Yeonbeum's public and private businesses) started right after Yoonsung appeared. That ought to be a huge red flag that Yeonbeum simply shouldn't be able to ignore.