It happened in quirk display class, which was already the worst possible setting for it.
The class was not combat, it was not theory, it was the one where students stood up one by one and performed a controlled demonstration of their quirk for the group while the teacher logged it on a performance record. Simple enough if you actually had a quirk. For Leo it was thirty minutes of sitting very still and calculating exactly how much of the pen device's output he could afford to use without drawing attention, and how far apart he needed to space the uses so nobody noticed a pattern.
He had done it before. It was not comfortable but it was manageable.
