The One Punch Man can't catch a break. Saitama, the most powerful hero in the world, isn't even the main character in his own game - figures. Here's how to unlock the entire roster of characters in One Punch Man: A Hero Nobody Knows, including how to play as Saitama.
There are 28 characters in total populating the One Punch Man: A Hero Nobody Knows roster, and most have their own unique battle style - or at least their own special moves. You'll be unleashing 20 heroes and 8 villains over 11 different stages.
The Standard Type fighters include the likes of Silverfang, Amai Mask, and the all-mighty Mumen Rider. While Metal Bat and Atomic Samurai both have there own versions of Weapon Type. Blizzard Bunch leader Hellish Blizzard and her S-Rank sister Terrible Tornado use variations of the powerful Psychic type, while you'll find the meatier characters on the roster like the Tank Tops using the Power Type.
Finally, there are three different types of Machine Type attacks. One for Genos-style androids, one for Child Emperor's backpack, and one for the hulking Metal Knight.
The evil characters most often use variations of the absolutely OP Monster Type, which you unlock for use with your own avatar by completing the game.
Some characters from the anime pop up in the game, but aren't usable as characters - chiefly King.
Like in the One Punch Man anime and manga, the characters are split up into ranks depending on their power level. Heroes are graded from Rank C to Rank S, while monsters can be Threat Level Tiger, Demon, or Dragon. Dragon is the strongest, with Tiger at the bottom.
Saitama though, is in a class all of his own. You can only pick him as the third member of your team, and he'll arrive late to the battle. But once he gets there he'll do what he does best: be completely immune to damage and beat everyone in one punch.
Below is the list of how to unlock every character, in the order which you unlock them during the game.
One Punch Man: A Hero Nobody Knows Character Roster Unlock Order
|One Punch Man: A Hero Nobody Knows character roster:||Rank:||Allegiance:||How to unlock:|
|Tank Top Tiger||C||Hero||Available from start|
|Tank Top Blackhole||B||Hero||Available from start|
|Crablante||Tiger||Villain||Available from start|
|Tank Top Master||S||Hero||Play through the early story missions|
|Silverfang||S||Hero||Unlocked next in story missions|
|Spring Mustachio||A||Hero||Continue through the main story|
|Stinger||A||Hero||After Spring Mustachio, Stinger will appear as a character on the map. Talk to him for a side quest and you'll unlock him afterwards|
|Vaccine Man||Dragon||Villain||Defeat him in main story mode|
|Handsome Kamen Amai Mask||A||Hero||After you beat Vaccine Man, a side quest appears in the Central Area outside the East third building that says "sweets" on - complete it for Amai Mask|
|Mumen Rider||C||Hero||Help him catch a purse snatcher in the main story|
|Metal Bat||S||Hero||Defeat the monsters after you unlock the furniture shop in main story mode|
|Mosquito Girl||Demon||Villain||Beat her in the main story|
|Genos||S||Hero||After Mosquito Girl, a Genos Special Mission appears at HQ. Complete it to unlock him|
|Saitama||?||Hero||Around the time in the main story that you reach rank B, you'll get a Saitama social mission which you unlock him after|
|Puri-Puri Prisoner||S||Hero||Puri-Puri Prisoner appears on the map after you unlock the south shopping street. Talk to him for a mission to add him to the roster|
|Hellish Blizzard||B||Hero||She's unlocked during the main story after you've unlocked the south shopping street|
|Terrible Tornado||S||Hero||After the Hellish Blizzard part of the main story, Terrible Tornado will have a Special Mission at the HQ|
|Carnage Kabuto||Dragon||Villain||Unlocked after the "Monitor the House of Evolution" main mission|
|Atomic Samurai||S||Hero||After the House of Evolution, unlock Atomic Samurai from a Special Mission at HQ|
|Child Emperor||S||Hero||After you first fight Speed o' Sound Sonic, you can speak to Child Emperor in the lobby at HQ|
|Snakebite Snek||A||Hero||Unlocked in the next run of main story missions after the Speed o' Sound Sonic|
|Speed o' Sound Sonic||N/A||Villain||Fought again in the main story after his Special Mission appears when you've fought him once|
|Metal Knight||S||Hero||Unlocked via a Special Mission at HQ after the Speed o' Sound Sonic fight|
|Deep Sea King||Demon||Villain||Unlocks after you beat him twice in story mode|
|Melzargard||Dragon||Villain||Also unlocks after you beat him twice in story mode|
|Boros||Dragon||Villain||Beat him in story fights to unlock|
|Saitama (Dream Version)||?||Hero||Complete the game|
If you want to play properly with Saitama's moveset, then you'll need to complete the game and unlock the Dream version. He is functionally the same as the regular Saitama, but deals normal damage and can take damage - but is still exceptionally good!