I know I have seen the first episode of Tougen Anki, but I have this fanfic. The Male Reader is a descendant of the Oni. Both him & his mother. His father is descended from Momotaro. He was murdered for having a relationship with an oni. He was killed by the other descendants from Momotaro when the Male Reader was just born. The reason is that he doesn't want to reveal the location. The mother got to the father only to see his lifeless body on the wall. She then picked up a picture next to him. She sees that it has the father, another woman & her child. The father was never happy with her. She kept the photo & left. Fast forward, the mother (with a beautiful look & personality from Rumi Usagiyama AKA Mirko from My Hero Academia) a business woman while the Male Reader is a weapon fanatics. He loves all kinds of weapons from Anime, TV series, Movie, Video Games, & Comic book. His mother told him to get dress so he can get ready for school. On his way to school, he was knocked out. He was kidnapped by 5 other descendants from Momotaro Agency. The Male Reader is waking up. One complaint that he should be killed for having Oni's blood. The other said that the commander would be very disappointed. The window shattered as the Mother, having black horns, shows up with a toothy grin. The mother demand that they free his son, only for the door behind the members to be opened by the woman in the photo. Her looks resembles of Artoria Pendragon (Lancer) from Fate/Grand Order & her personality is that of an ice queen. The two women decided to take it outside. The commander then nodded. The mother then went outside as the commander told them no one kills the Male Reader. The Mother & The Commander have a fierce battle. The commander is impressed by the mother. Even after hiding for so long, she hasn't missed a step. The first descendant is impatient as the battle reach it end. Both women double K.O. each other, yet still breathing. The first descendant didn't wait & stabbed the Male Reader. The Male Reader is about to die, but then he awakened his Oni power & kill the first descendant. He created Ruby's Crescent Rose & take kill the other 3 descendants. The final descendant was surprised as the Male Reader recreated King Dedede's final Smash in SSBU, by smacking him to the wall, launch dozen of missiles as him, & slam his hammer, cause the wall to explode. The Mother & the Commander saw this as the Commander then use Black Mist to flee.  The Male Reader then went to his mother, who is proud about his awakening. She then calm down by putting her hand on his face, calming him down. Naito Mudano appeared behind the mother. Naito asked about it & the Mother told him the truth. Despite being a difficult person to impress, he is curious about her son as he stated, "The apple doesn't fall too far from its tree." Naito wanted to test the Male Reader. The Mother asked how many students. He answered 4 students, with both Shiki Ichinose & The Male Reader about to be interviewed. The Mother asked about any available facility at Rasetsu Academy. Naito will talked to the director about it. The Mother gave Naito her son as she then got up with wounds. She will go pack at the house while Naito takes the Male Reader to Rasetsu Academy. The Journey to master his Oni blood begins.

That's an incredibly detailed and action-packed start to a fanfiction! It sets up a compelling conflict with the Momotaro descendants, a fascinating family dynamic, and an exciting premise for the Male Reader's journey to master his Oni powers.
Here's a breakdown of the key elements and what makes them work:
Strengths of your fanfiction concept:
* High Stakes and Emotional Core: The murder of the father right at the Male Reader's birth immediately establishes a deep-seated conflict and emotional trauma. The mother's discovery of the photo adds another layer of complexity and potential future drama.
* Unique Character Concepts:
   * Male Reader: A weapon fanatic with Oni blood is a fantastic combination, offering a lot of potential for creative action sequences (like the Crescent Rose and King Dedede's Final Smash!). His awakening is perfectly timed for maximum impact.
   * Mother (Mirko-inspired): Her design and personality sound incredibly strong and capable, making her a formidable protector and a cool character in her own right. Her black horns are a great visual touch.
   * Commander (Artoria Lancer-inspired): An "ice queen" Momotaro descendant provides an excellent foil to the mother, and their double K.O. fight is a fantastic way to showcase their power.
* Dynamic Action Sequences: You've clearly envisioned some intense battles, from the mother's dramatic entrance to the Male Reader's explosive awakening. The specific weapon recreations are a brilliant touch for a weapon fanatic character.
* Intriguing Plot Hooks:
   * The "other woman" and her child from the photo introduce an immediate mystery and potential future conflict or alliance.
   * Naito Mudano's appearance and the introduction of Rasetsu Academy set up the next major arc: the Male Reader's training and integration into the wider world of Oni descendants.
   * The mother's continued involvement and her connection to Naito and the academy are also great for ongoing plot development.
* Clear Motivation: The Momotaro descendants' hatred for Oni blood provides a straightforward, yet effective, antagonist motivation.
Things to consider as you develop this fanfic:
* The "Other Woman": The presence of the "other woman" and child in the photo is a significant reveal. How does the mother react to this emotionally, beyond just keeping the photo? How will this impact the Male Reader's understanding of his father? This could be a powerful emotional arc.
* The Momotaro Agency's Goals: Beyond just killing Oni, what are their larger objectives? What is the "commander's" true agenda, especially given her reaction to the Male Reader's power?
* Rasetsu Academy: What kind of academy is it? What are the training methods like? How will the Male Reader fit in with the other students, especially Shiki Ichinose? Will there be challenges from within the academy itself?
* Male Reader's Powers: You've shown he can create weapons. Are there other aspects to his Oni power? Does he have enhanced strength, durability, or other unique abilities beyond weapon manifestation?
* The "Double K.O.": While a great way to end the fight without a clear winner, consider the immediate aftermath for both women. How do they recover, and what are their long-term injuries or consequences from such a fierce battle?
This is a fantastic foundation for a fanfiction! You've got a compelling hero, powerful women, and a clear path forward for an exciting story.