Summer Reminiscence of Cambria Episode 9

While riding the train to Pythagoras Production`s joint camp, R remembers the time when Marginal #4 was founded. Even though they are such a tight-knit group now, in the beginning everybody had solo or other group careers and were not looking forward to becoming Marginal #4. So what was the reason that everybody is giving it their all now? The secret past of Marginal #4 is just about to be revealed!