Warner Bros. Japan handled the home video releases for the Prison School anime series with six singles that came out ending in early 2016 and they recently set up a complete collection.
With the Blu-ray singles running 7,000 yen each over six discs previously, this is definitely a good deal.
Plot concept: Hachimitsu Academy, known for its strict academic standards and even stricter school code, is making a giant change this year.