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Under Ninja Author Kengo Hanazawa Puts a Spotlight on Seinen Manga

When writing Under Ninja, Kengo Hanazawa pays special attention to sound effects — specifically, the lack of them. “I wasn't able to depict this perfectly at the beginning,” he said at his Anime NYC 2025 panel, “but ninjas are known to be silent.” Where other manga go heavy on onomatopoeia, in Under Ninja, the stronger the ninja, the fewer and subtler the sound effects.

Hanazawa claims he's not a ninja himself — that career would be “too difficult” for him — but at points in the panel, one might mistake him for one. He arrived cosplaying his series' protagonist, Kuro Kumogakure (photos weren't allowed), and his panel was the quietest I attended at the con this year. Being interviewed by Ed Chavez, the president of the manga's American publisher DENPA, the author described himself as a “dark introvert” who is “honestly not fit for society,” akin to many of his characters. You could sense his curious awkwardness as he quietly and thoughtfully answered questions.

Two editors from Japanese publisher Kodansha, Yamanaka and Yamada, were also present on the panel but mostly quiet, occasionally elaborating on some of Hanazawa's briefer answers. Chavez directed one question to the editors on how they'd describe Hanazawa. Yamanaka answered that Hanazawa is “a proper manga artist and he's got a good personality,” while also noting that, unlike some other manga artists, Hanazawa would not be able to “go out in society if he wanted to.” Yamada praised how Hanazawa is “giving his stories a lot of thought” and is a “really wonderfully talented person.”

Being quiet and weird is fitting for what makes Under Ninja and other Hanazawa manga distinctive. The inspiration for Under Ninja, Hanazawa explained, came about feeling exhausted after completing his previous long-running manga I am a Hero, and one of his editors casually mentioned, “Ninjas, is that something you'd be interested in?” That comment sparked inspiration, but Hanazawa didn't go about writing his ninja story as the big action-adventure story one might expect. He knew he wanted to set the first scene in a “broken down shoddy apartment,” focusing on someone who's “dull [and] not terribly ambitious.” His main inspiration? Maison Ikkoku.

While Under Ninja has a lot more violence and a lot less romance than Rumiko Takahashi's classic romcom, Hanazawa claimed Under Ninja was conceived of as “more of a slow-paced manga,” even “peaceful.” Under Ninja has become more of an action series as it's gone on; this shift in direction, Hanazawa explained, is one of the advantages of writing seinen over shonen. Where shonen manga have to introduce their premise in the first chapter, seinen manga have the freedom to introduce the story more gradually and focus on character over plot.

Hanazawa characterizes working full-time as a manga artist for Kodansha as tiring, but with “minimal stress.” A typical day for Hanazawa involves waking up at 6 AM, taking his kids to school, then working from 9:30 AM-5:30 PM, and after having dinner with family, doing even more work up until midnight. When he gets too exhausted to work, he tries to “find a change of scenery” and “do something completely separate from manga.” He catalogues interesting ideas that come to mind during these breaks and will sometimes come back to use them in his manga to prove “realism and deeper meaning.” One of his editors chimed in to predict that the photos he took in NYC this trip will almost certainly inspire some future manga.

The fan question and answer portion of the panel contained several questions asking when Hanazawa came up with certain spoiler-y twists in Under Ninja. One twist he had vague ideas of at the beginning of the series, while another he only decided much later on, for the sake of a surprise. Hanazawa's favorite thing to draw in the manga was a “particular water technique” (likely referring to the Water Escape Technique). When asked about his thoughts on AI, Hanazawa was clear that he doesn't use it, and will only consider using AI when it's “ethical” in regard to licensing and rights.

Hanazawa's closing words for the panel spoke about the seinen genre in general, which Kodansha has been promoting heavily at Anime NYC with their giveaways of the first American issue of Young Magazine (Under Ninja's first chapter is included along with 18 new one-off stories.) "Seinen manga is something that has yet to spread very far overseas. We'll try to spread further in the future. There are a lot of manga in Japan left to be discovered. Manga has such a depth of range. I want you to read not just my work, but tons of other manga. The more you read, the more you'll discover just how deeply the culture of manga goes."