Masaki is a man with messy brown hair and black eyes. His hero costume consists of a blue and white, skin tight, long sleeved shirt that tucks into his orange gloves. He wears dark pants, white boots and sports a signature helmet that features a fish-like fin and blue visor.
Manual has a very kind, attentive, and ordinary personality. He has an inspiring attitude, as he wants to become a role model for all modern heroes and can complete any tasks simply. In the extras, it is revealed that Manual chose Tenya Iida because he feels similar to Tenya. He also has a very keen mind, and could figure out the reason that Tenya chose his office was to find Hero Killer: Stain.
A year prior to starting his teaching career, Shota Aizawa was called into a meeting with Best Jeanist, Manual, Desutegoro, Snipe, Thirteen, Endeavor, Air Jet, Midnight, Ingenium, and Gunhead. They were there with an unnamed police officer to speak about the victimized civilians injected with Trigger drug.
Following the U.A. Sports Festival, Manual sent Tenya Iida and internship opportunity at his very own Hero Agency in Hosu City. Tenya accepts, and on the first day of their field training, Manual takes Tenya out on patrol. He tells Tenya that he is very excited to be mentoring Ingenium's younger brother, and is confused as to why Tenya wouldn't have chosen a more famous hero to intern with.
When they return to Manual's office at night, he tells Tenya that the city remains on high alert so the criminals have been reluctant to come out. When they patrol Kyoto together the next day, Manual admits that he knows Tenya only chose his agency to avenge his brother.
The Hero Killer: Stain attacked Ingenium in Hosu City, and Manual was able to deduce that Tenya only wanted to intern in Hosu to go after him. He says that he's glad Tenya chose his agency, but also informs Tenya that he shouldn't be pursuing personal grudges. He goes on to lecture Tenya about the regulations on Quirks, and states that a hero must not use their Quirks for themselves because if they did, it would be a very serious crime. Tenya replies that he understands, and so Manual lets it go and they continue patrolling.
When chaos ensues in Hosu and buildings start going up in flames during their patrol, Manual receives a message that villains have appeared in the city. He responds and decides to head to the battle zone himself. He tells Tenya to accompany him, but does not notice that he has run off by himself until he arrives at the center of the destruction.
Manual and several other Pros face off against the culprits, two Nomus with incredible strength. With just the two of them, the pro heroes have their hands full. Manual notices Tenya is missing and calls out to him, but is forced to put his focus on fighting the fires created by the monsters.
During the battle between the heroes and the monsters, Manual notices one of them about to crush a fellow hero. He calls out to her, but Endeavor arrives to save the day. 
Once the chaotic incident finally ceases, Manual and Gran Torino visit Tenya, Shoto Todoroki and Izuku Midoriya at the hospital. The three of them managed to defeat the Hero Killer, but were still liable to repercussions. Police Chief Kenji Tsuragamae explains all six of them including Endeavor would be punished if the incident went public.
However, Kenji allows the incident to remain confidential and thanks the boys instead. Afterwards, Tenya takes a moment to apologize for neglecting Manual's advice. Manual sheds a tear, knowing he has to take responsibility as a supervisor for his negligence. He chops Tenya in the head, telling him to never do it again.
Quirk and Abilities
Unnamed Hydrokinetic Quirk: Manual's Quirk appears to allow him some level of hydrokinesis. Although unlike Backdraft, he appears to need an outside source of water and is unable to produce it himself.
Battles & Events
Field Training Arc
- Manual and other Pro Heroes vs. 2 Nomus: Indecisive
- He likes balance and houseplants.
- Kohei states that he likes drawing Manual despite him being a side character.
- Manual's Pro-Hero name is not belittling according to Kohei.
- From Mizushima, 水 means water and 島 means island. From Masaki, 正規 is read as Masaki but can also be read as Seiki which means regular/normal.
|Heroes||All Might • Air Jet • Backdraft • Best Jeanist • Buster Hero • Cementoss • Crimson Riot • Desutegoro • Ectoplasm • Edgeshot • Endeavor • Eraserhead • Fat Gum • Fourth Kind • Gang Orca • Gran Torino • Gunhead • Hound Dog • Ingenium • Kamui Woods • Kesagiriman • Lunch-Rush • Mandalay • Manual • Midnight • Mount Lady • Mr. Principal • Ms. Joke • Native • Thirteen • Pixie-Bob • Power Loader • Present Mic • Ragdoll • Recovery Girl • Rock Lock • Ryukyu • Sir Nighteye • Snipe • Tiger • Uwabami • Vlad King|
|Anime Original Heroes||Lucky Strike • Mick • Romero Fujimi • Selkie • Sensor Girl|
|Sidekicks||Bubble Girl • Centipeder • Sirius|
|Hero Teams||Pussycats • Team Idaten • Water Horse|
|Unofficial Hero Teams||Hideout Raid Team|
|Related Articles||Costume • Hero Name • Hero Office • Quirk • U.A. High School|