If you're looking for manga similar to Ultraman: Chou Toushi Gekiden - Suisei Senjin Tsuifon Toujou, you might like these titles.
Relish is an evil organization plotting world domination. The organization’s mad scientist Dr. Takizawa uses a cell-restructuring device on a young man named Katagiri in hopes of creating a superhuman, but the experiment is a failure. After fleeing the organization, Katagiri is astonished to find that when night falls, his whole body turns jet black and he gains incredible strength and the ability to jump to great heights! Now as Shadowman, Katagiri begins to fight against Relish...
A hero who manages world peace. There were twins who longed for their overwhelming power and vowed to “become a 'hero.'" However, a few years later, his younger brother, Yosai, broke his dream and became a cleaning worker to clean up the heroes. Yosai tells herself that she has a position (rank) that was decided by nature, with her brother who became a hero sideways. However, when I saw the despair of my important childhood friend, the dolphin, I was prepared to go against that fate with the first and last resolutions!
Since the government announced the existence of people with “special powers” 10 years ago, Shindo Susumu has longed for his own amazing abilities. However, he finds himself to be nothing but an average 15-year-old. Then one day, during his high school entrance ceremony, a power finally awakens inside him…but it’s not exactly the kind he’d always hoped for!
Koichi Haimawari couldn’t make the cut to become an official hero, so he uses his modest Quirk to do good deeds in his spare time. Then one day a fateful encounter with some local thugs leads him to team up with two other unlikely heroes. None of them really know what they’re doing, but they’ve got the courage—or foolishness—to try. But they soon discover fighting evil takes more than just being brave…
Rokurou, the class cockroach (figuratively speaking), is visited at night by an alien girl who bestows magical powers upon him! Finally, he can ascend from his status of a complete nobody to the town's unique super hero! … Right?
In Sternbuild City, corporate logos not only cover billboards, but also the costumes of the super-powered heroes that act as its protectors. Veteran and newcomer warriors of justice alike compete in a reality TV show that offers points for apprehending criminals while giving champions' sponsors a chance to promote their brand. When the low-ranking Wild Tiger loses his backing after a string of outrageous, botched rescues, he finds himself paired with an up-and-coming spotlight-seeker called Barnaby. But with their wildly different personalities, will the pair be able to save their beloved Sternbuild City and win the game show, or will their constant tension be the undoing of the world's first hero team?
Long ago, when danger approached the Earth, there existed people exhibiting their superhuman powers to save the planet; to help the weak; to defeat evil and to promote justice. Earth never hesitated to sacrifice such beings. The powerless set these people apart and honored them by calling them heroes. However...the era somehow changed...
From Birdman, a superman from space, he received a mysterious mask and cape. Wearing these, even a slightly clumsy elementary student can transform into Perman, a hero of justice! Rescue the weak, thwart the evil. Together with his three friends, Perman does his best every day to protect peace on Earth!