Satoko, a naive kunoichi from a hidden ninja village, escapes from her home after being clumsy and distracted, which causes her to run away unintentionally. While fleeing through the forest, she is pursued by skilled ninjas sent to kill her for her betrayal. During her escape, she encounters Konoha, a high school girl assassin who is initially bored and indifferent. Konoha finds Satoko collapsed and starving, mistaking her for a corpse at first. After some convincing, Konoha takes Satoko under her roof, and they begin living together, despite their very different personalities and skills.

Konoha, who is highly skilled and stoic, quickly adapts to the danger Satoko brings. She kills the first ninja assassin who comes after Satoko with swift and efficient violence, using her assassin skills without hesitation. Satoko, meanwhile, is mostly helpless in combat and relies on Konoha for protection. Konoha also gives Satoko money to go clothes shopping at the mall, where they encounter another ninja assassin named Asuka. Konoha kills Asuka in a quick confrontation, demonstrating her lethal efficiency.

Satoko later reunites with Kuro, the leader of the rogue ninjas who orchestrated her escape from the village. Kuro is also Satoko's lover, and Satoko moves in with her briefly. This reunion causes tension between Satoko and Konoha, leading to an argument over Satoko's loyalties and future.

During this time, another ninja assassin named Midori, disguised as a restaurant worker, attempts to poison Konoha to get to Satoko. Konoha sees through the disguise and kills Midori in broad daylight. The killing causes a scene, but Kuro uses her ability to erase the memories of nearby witnesses, preventing any consequences from the public killing.

It is revealed that Midori and Asuka were friends enjoying a girls' night with Fumiko, another ninja assassin working under a figure named Fumiko, when they received orders to hunt Satoko down. This shows the network of assassins and ninjas involved in the pursuit.

Throughout the series, Konoha remains calm and professional, taking on assassination jobs and protecting Satoko from various threats. Satoko's clumsiness and naivety contrast with Konoha's cold efficiency, creating both tension and humor. Konoha's kills are often shown with minimal gore, usually just a stabbing sound followed by Satoko turning the bodies into leaves, highlighting the dark humor of the series.

The story progresses with multiple confrontations as more ninja assassins arrive to eliminate Satoko. Konoha kills each one with precision, while Satoko struggles to find her place and prove her worth. The relationship between the two deepens as they navigate the dangers of their lives under one roof, balancing moments of violence with comedic and emotional interactions.

The final episodes focus on the escalating conflict with the ninja village and the rogue ninjas, culminating in a decisive confrontation where Konoha and Satoko must rely on each other's strengths to survive. The series ends with them solidifying their bond, continuing their life together amid ongoing threats, with Konoha as the protector and Satoko as the hopeful but clumsy ninja trying to find her way.

The ending of A Ninja and an Assassin Under One Roof shows Satoko and Konoha recovering from their battles and injuries, reaffirming their partnership and friendship. Konoha admits her deep care for Satoko and reveals her personal motivation for climbing the assassin ranks, though the exact reason is left undisclosed. The series closes with the two working seamlessly together, stronger and happier despite the scars they bear, symbolizing their growth and mutual support.

The final episode begins with Satoko receiving medical care for her injuries, including a scene where she experiences going to the dentist for the first time, highlighting her vulnerability after the intense conflicts. Meanwhile, Konoha faces off against a formidable ninja doppelganger resembling Haruko Haruhara from FLCL, who has prepared countermeasures against Satoko's ninja powers. This confrontation serves as the climactic action sequence, showcasing Konoha's growth and strategic thinking.

During the battle, Konoha and Satoko demonstrate how much more effective they are when working together rather than alone. The fight culminates with the triumphant return of Konoha, who manages to overcome the doppelganger's attacks, solidifying her role as Satoko's protector.

After the fight, Konoha openly admits to herself and Satoko that she cares deeply for her. She breaks a "death-flag" by sharing the reason behind her desperate ambition to rise in the assassin ranks, though the series deliberately withholds the specific details of this reason. This moment is significant because it shows Konoha's willingness to be vulnerable and trust Satoko, who accepts her without judgment.

The episode closes with the two girls continuing their partnership, now more united and emotionally connected than ever. Their physical and emotional scars are portrayed as marks of growth and testament to their bond. Although Konoha's goal of becoming a top assassin remains distant, both characters are shown to be infinitely happier than at the series' start, marking a personal victory beyond their external conflicts.

In terms of character fates:

• Satoko Kusagakure recovers from her injuries and remains by Konoha's side, continuing to use her ninja skills to support their shared life.
• Konoha Koga survives the final battle, reveals her inner motivations, and commits to her path as an assassin with Satoko's friendship as a source of strength.

No other main characters directly participate in the ending's resolution, as the focus remains tightly on the evolving relationship and mutual support between Satoko and Konoha.

Yes, the TV show A Ninja and an Assassin Under One Roof (2025) includes a post-credit scene. This scene is a lighthearted sketch featuring the characters Midori, Asuka (the blonde ninja assassin), and another female character from earlier episodes. Despite these characters being killed off during the main storyline, the post-credit sketch allows them to appear again in a humorous context, effectively keeping their presence alive beyond their narrative deaths.

Satoko Kusagakure escapes her ninja village because she is considered useless in the ninja field and forced to do unskilled work. After her escape, she is pursued by multiple ninja assassins sent to kill her for her betrayal. This leads to her being rescued by Konoha Koga, a high school assassin, and the start of their unusual cohabitation. The pursuers include skilled ninjas like Asuka and Midori, who attempt to kill Satoko and Konoha but are defeated, with Kuro, the rogue ninja leader, erasing witnesses' memories to cover their tracks.

Konoha Koga, a high school assassin, skillfully defeats every ninja assassin sent after Satoko. She kills Asuka at the mall and sees through Midori's poisoning attempt, killing her in broad daylight. Konoha's kills are depicted with a comedic contrast: the animation shows detailed attacks, but the actual kills are silent and understated, often followed by Satoko turning the bodies into leaves. Konoha remains stoic and unphased by the danger, protecting Satoko effectively.

Konoha and Satoko live together under one roof after Konoha rescues Satoko. Satoko is naive and clumsy, while Konoha is subdued, serious, and blasé about their dangerous lives. Their contrasting personalities create humor, with Satoko often getting the worse end of the partnership. Konoha uses Satoko for her ninja skills despite Satoko being largely ineffective in combat. Their relationship is marked by mutual dependence amid constant threats from Satoko's former village.

Kuro is the leader of the rogue ninjas who plotted Satoko's escape from the village so she could live with her lover. She has the ability to erase the memories of nearby witnesses, which she uses after Konoha kills Midori in public to prevent exposure. Kuro's involvement adds complexity to the pursuit of Satoko, as she supports Satoko's defection and protects her from the village's assassins.

Notable encounters include the fight at the mall where Konoha and Satoko kill Asuka, another ninja assassin. Midori, disguised as a restaurant worker, attempts to poison Konoha to get to Satoko but is killed in broad daylight. These encounters showcase the variety of ninja assassins pursuing Satoko, including poison users, weapons masters, and transformation experts. Each encounter highlights Konoha's lethal efficiency and Satoko's precarious situation.

The TV show A Ninja and an Assassin Under One Roof (2025) is not fully family-friendly and contains content that may be objectionable or upsetting for children and sensitive viewers. It features violence including scenes of murder, bloodshed, and combat involving weapons like shuriken and kusarigama, as well as themes of assassination and ninja pursuits. The show also explores darker emotional themes such as survival, orphanhood, and the psychological struggles of its characters, including a high school assassin dealing with the consequences of her actions.

Potentially upsetting aspects include:

• Graphic violence and blood in fight scenes, including killings.
• Themes of death, revenge, and danger from pursuers.
• Emotional intensity related to trauma, loss, and survival struggles.
• Some mature themes around assassination and criminal activity.

While the animation style may appear cutesy or modern, the content is more suited to older teens or adults due to these mature and violent elements. It is not recommended for young children or highly sensitive viewers.