Gewalt - Aoiro Terror x Seishun Graffiti!!
Ruito is an ordinary high school student. Too ordinary... almost transparent. But when one day, thugs are attacking him before his supposed "friends", he is humiliated, exposed; his true nature is revealed, he realizes that his social life is now impossible. Then lost, Ruito decided to move the "other side", the hard, the violent side. But during his initiation, between satisfaction and doubts, meetings and missteps, despite himself Ruito will awake old rivalries and start what could become an open war! (Source: manga-sanctuary.com)
Mazinger Z : Relic of Terror
An bonus chapter included with the final volume of Getter Robo Āḥ. Dr. Hell discovers a biomechanical lifeform known as "Kedora" in the depths of Bardos Island, and realises that he can use it to fight Mazinger Z. The story of this chapter was loosely adapted into the sixteenth episode of Shin Mazinger Shougeki! Z-Hen.