Tsuujou Kougeki ga Zentai Kougeki de Ni-kai Kougeki no Okaasan wa Suki Desu ka?

Teenage boy Masato Oosuki was chosen to beta test a new MMORPG, where you're actually teleported inside the world of the game. But once he gets there, he finds his mother has followed him, and she's incredibly strong, too.

Mamako and Masato are now registered as hero and mommy, and they decide to have an interview to decide who’ll join their party.

Wise joins the party as they prepare to visit the village of Maman on a special quest that Shirase gave them. But first they have to buy equipment, and Mamako is overjoyed at the idea of going shopping with her son.

The "Empress of Night" turns out to be none other than Wise's mother, who she split up with after a fight. When the two of them went their separate ways, the Empress decided to stop playing the game and instead go chasing after attractive men.

Masato, Wise, and Porta become students at Lover’s Lane Academia. Studying here will give them lots of SP and tons of special items. At school they meet a sweet and shy healer named Medhi, and Masato is convinced he’s found the true heroine.

With Shirase’s help, Mamako is allowed to attend the school as well. Just like Medhimama, she becomes an observer in Masato’s class. When Medhimama finds out that her magic doesn’t work on Mamako, she decides that Mamako is her new rival.

The person who’d been whispering her hate about Medhimama was actually Medhi herself. Medhi was loyally doing what her mother told her to, but was secretly feeling extremely stressed and angry. When Masato and his mom find out about this, they decide they want to help her. Meanwhile, the school holds a festival, and parents are allowed to participate. The group decides to open a small café where Mamako will cook. Medhimama opens a café of her own, and insists on competing with Mamako to see who can sell more. Mamako reluctantly agrees, but…

Medhi was able to say what she felt about her mom when Masato was around, but in front of her mother, she always forced herself to act obedient. Wise and Porta both try to cheer her up and be her friend, but Medhimama, who wants a good daughter so that she can become “the number one mom”, refuses to let her have any friends. When Medhi realizes that her mother’s fanaticism was just for the sake of her own ego, she breaks down, lets her feelings loose, and becomes a powerful dragon. The party tries to stop her, but even in the middle of the fight, Medhimama is so obsessed with being number one that she challenges Mamako to a duel!

Medhi decides to come along with Masato and the party. They all get a notice about a new "tower dungeon", which will grant any wish to those who can get to the top. The party heads to the town of Ommym, where the dungeon awaits. As soon as they arrive, a group of mothers begs them to look for their children. Shirase says that this isn’t part of any event, however. They decide to investigate the dungeon with her. As they get past the traps and the monsters, they’re met by a woman dressed like a gladiator.

The girl who stood in the party's way announced herself as "Amante, Betrayer of Mothers", and told them that she belonged to the rebel group "Ribele". She also told them that she'd gotten the adventurers in town to join her party and help her clear the dungeon. She told them all this despite the fact that they hadn't asked her any of it. The party decided that it needed lots of help to free the adventurers from Amante, and retreated. They opened the "With Mommy" guild, and began to recruit. But Amante's helper, Pocchi, came to stop them. He and his buddies made a certain demand of Mamako, and told her that if she didn't do what they wanted, they’d use bombs to blow up the city!

After being touched by Mamako's motherly kindness, Pocchi and his friends changed their ways and went home to their mothers. As a way of saying thank you, the mothers agree to join the With Mommy guild, and help the party clear the tower. There are still a lot of children who are working for Amante. And so the party, now filled with mothers, heads off to the tower, gossiping and chatting all the way. When this not-very-adventurous party makes it inside the dungeon, they’re met by Amante, who’s gotten sick of waiting for them. She challenges Mamako to… a washing and cleaning contest?!

Masato's party makes their way up the tower. They meet Pocchi on the way up, who tells them that Amante's plan is to clear the dungeon and wish for all mothers to disappear. They have to stop her! Meanwhile, Amante has made it to the top of the 100 floor tower, and defeated the last boss, but she can't get into the wish-granting room. Masato's party arrives and challenges her to a duel. During the middle of the battle, Amante tells Mamako that her presence here is stealing away her son's future! Mamako is caught off guard. But instead, Masato...

To thank the group for all their hard work in the past, Shirase invites the party to enjoy the sunny beach. While enjoying the wonderful weather and pristine waters, an accident causes Masato to lose all his memories, including those of Mamako!