A Ninja and an Assassin Under One Roof episode 12(finale) is set to be released on Thursday, June 26, 2025, at 10:30 pm JST, according to the series' official website. The previous episode picked up where episode 11 left off - Konoha was still affected by becoming a baby. She needed to regain her assassin self and thus set out overseas to complete different assignments.
Although formal leaks for television anime series of the Spring 2025 season are unlikely, the release information for A Ninja and an Assassin Under One Roof episode 12 has been officially confirmed.
A Ninja and an Assassin Under One Roof episode 12 release date and time

A Ninja and an Assassin Under One Roof episode 12 will air on Japanese television networks at 10:30 pm JST on Thursday, June 26, 2025. However, some may get to witness the latest episode quite early on the same day. The exact time of release will vary with time zone and region.
A Ninja and an Assassin Under One Roof episode 12 will release at the following schedule in the corresponding time zones:
Where to watch A Ninja and an Assassin Under One Roof episode 12?

According to the main promotional video release, A Ninja and an Assassin Under One Roof episode 12 will first air on AT-X on June 26, 2025, at 10:30 pm. It will then be broadcast on BS11 about two hours later, on June 27, 2025, at 12:30 am, followed by KTV at 1:45 am JST the same day. The episode will also be available on Crunchyroll.
For international viewers, the series will be available on Hulu, Prime Video, Plex, and many others. However, these platforms will require a subscription.
A Ninja and an Assassin Under One Roof episode 11 recap

Titled "A Ninja and An Assassin's Big Dilemma", the episode began with Konoha behaving strangely with Satoko. She stayed awfully close to the Kunoichi and even suggested going shopping, wearing the dress Satoko had gifted her. Consulting the Izutsumi sisters revealed that Konoha was still affected by what had happened.
Given that she (presumably) had a lonely childhood, her baby self was affecting her normal self. In other words, she involuntarily yearned for the love and care she had received from Satoko. So much so that she had stopped her assassination work. Whilst out shopping, Satoko revealed the truth to her.
However, that angered Konoha and stormed off. But the pair weren't separate for too long as Konoha snuck up on a ninja pursuer behind Satoko. Though she had forgotten how to kill, resulting in her sustaining a grave injury and Satoko saved her. Later on, Konoha decided to accept the organization's invitation for special missions.

She needed to return to her assassin ways, and this was the only way. Thus, she set off overseas to take on the invite, rise up the ranks, and regain her status. Konoha travelled, completed missions, and fulfilled objectives whilst keeping in touch with a hopeful Satoko.
Back in Japan, the Kunoichi and Marin visited Kuro. Satoko wanted to be useful to Konoha when she returned, and to do that, she opted to borrow Kuro's weapons. Their interaction also vaguely touched on why the ninja were after her. The episode ended with a glimpse at Konoha, who was attacked while completing a mission.
What to expect from A Ninja and an Assassin Under One Roof episode 12?

A Ninja and an Assassin Under One Roof episode 12 will be the final installment of the anime. Since it is the last one, there are no official previews revealing what fans may see.
However, given the previous episode's events, Konoha will have to fight her way back to return home to Japan, to Satoko. A Ninja and an Assassin Under One Roof episode 12 will reveal whether or not she has regained her assassin status and her goals, too (once she reunites with Satoko). There will be a Satoko-Konoha bonding moment and a possible glimpse at Konoha's origin story.
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