Sensei no Bulge

Sensei no Bulge (戦星のバルジ, Sensei no Baruji, lit. "Bulge of the Battle Star"), otherwise known as Barrage, is a Japanese manga written and illustrated by Kōhei Horikoshi. Sensei no Bulge was first published as a oneshot under the name Uchū Shōnen Bulge in the Summer 2011 edition of the Jump NEXT! magazine. It was then serialized on the Weekly Shōnen Jump magazine starting in issue 25, released May 2012.

Plot
The planet Industria was peacefully ruled by a royal family until its inhabitants made contact an evil alien race. Since then, for over fifty years, the planet has been in a constant state of war.

In the planet's capital, Astro is a destitute working for peanuts, struggling to make ends meet with the many younger brothers and sisters he had adopted into a family. His boss encounters an alien archduke from nearby who nearly crushes him to death. Astro saves his boss, to which the archduke mocks his poverty and throws him his wallet, to the presence of a few royal guards. The boss fires Astro for causing him trouble despite being saved by him. That night, Astro tries to break the bad news to his brothers and sisters, but fails as they express their gratitude for Astro's hard work in raising them. Later, Astro sits on the rooftop contemplating where to find his next job when one of his sisters, Chima, offers him an apple. Astro refuses her offer, having nothing to give her back in exchange, though he yearns to return her offer with happiness and luxury. Suddenly, having overheard their conversation, a hooded figure reveals himself to the two as Bulge, the prince of Industria, who happens to have the same appearance and voice as Astro. Bulge offers Astro to be the new prince of Industria and rule the planet, leaving himself to laze around for the rest of his life. Before Astro knew what was happening, Bulge straps his arm with the "Org", the "King's Tool". Just after Bulge boasts his freedom from the kingdom, he is assassinated and his body falls off the roof. Just then, the royal guards find Astro and take him away, mistaking him for Bulge. The silhouetted assassin is confused at the situation and disappears.

Meanwhile, the alien archduke pays a visit to the Planetary King of Industria, requesting the Org from him. The king refuses and tells him to leave. A vice-captain of the military police unit, Tiamat, reports of Bulge's return. Astro is taken inside the castle, finally realizing that Bulge really was the prince after all. Realizing he may be accused of murdering Bulge, Astro attempts to play along as Bulge while still trying to escape. Unfortunately, Tiamat catches Astro and sends him to his room. Along the way, the alien archduke spots Astro and hatches a new plan to take over Industria. Astro realizes Bulge's intentions of defecting from the royal family and scolds Tiamat for having told him he isn't needed. Just as Tiamat is surprised by his reaction, the alien archduke attacks the castle, claiming their prince had stolen his money. Tiamat rushes outside to confront him while the king contemplates submitting to the archduke. The archduke refuses a physical battle with Tiamat and calls the prince out to confront him. Astro considers taking the opportunity to flee home, but eventually refuses and lunges at the archduke. The Org suddenly activates and Astro finds himself carrying a large trident. With it, he easily defeats the archduke and throws him back his wallet, to which everyone realizes it was the archduke who dropped it himself. Astro demands an apology from the archduke, but realizes he had cornered himself into his new job as the prince of Industria.

Official

 * Japanese Shonen Jump Sensei no Bulge website
 * English Shonen Jump Barrage website