The Punishment Classroom (Pure) Game Over is an ending which occurs if Eric(a) is sent to the Punishment Classroom again after having already gotten three pure points during previous visits.
Back for another lesson the Teacher prepares Eric(a) once more to empty their head of "useless knowledge", to help their mind match their body. A body that within this classroom has regressed to being an eleven-year-old girl. Rather than learning anything new, the older Eric(a) has knowledge and memories stripped away bit by bit to become closer to that of a child's. Even their personal memories are not spared in the long time spent in the classroom.
By the time Eric(a) exits to the real world, only the mind of an eleven-year-old girl remains, much to Marianne's confusion. Eventually they are transferred away to be trained at the Magical Café in Japan, with Director Ayame happily giving her a new body to match her mind.