Requirement(s): Week 3+, Viewed stalls 4+ times, spoken to Natasha before
Location: New Lark Mall>Full Moon
Peep on the “Out of order” stall in Full Moon clothing store in the morning after the requirements have been met. You must have peeped on people in the other stalls at least five times before.
With Naira's PC I seem to remember always having that dialog option available, it's an excuse to get in to her room when she's not there.