Today, the MarriageToxin Project announced the release of an all-new main visual, first trailer and additional main staff and voice cast for the anime series adaptation of hitman/marriage swindler/battle-action manga, MarriageToxin. The series written by Joumyaku and illustrated by Mizuki Yoda is currently serialized on Shueisha’s manga app Shonen Jump+ and will begin airing as a TV anime in 2026.
The newly revealed main visual offers a glimpse of the action, depicting protagonist and assassin Gero poised with his signature weapon, a poison needle, and marriage swindler Kinosaki holding a ring box.
The first trailer features a lineup of deadly assassins who stand in the way of the strongest duo brought together by the underworld, as well as charming characters who appear throughout Gero’s ultimate mission of marriage hunting. It also includes battle sequences that showcase the elite skills of Gero, a top-class assassin.
The anime from BONES Film (My Hero Academia, Gachiakuta) welcomes Anna Nagase, Mariya Ise, Asaki Yuikawa, Soma Saito, Hinano Shirahama and Simba Tsuchiya to the cast list to voice a range of characters:
Kyoko Himekawa (voiced by Anna Nagase) works to recover art that has been unjustly taken and return
it to its rightful owners. Highly skilled in communication, she can become friends with anyone, yet rarely
speak much about herself. She has a deep love for sharks, and collects shark-themed merchandise and
movies.
“When I first read the original manga, I was surprised by the unexpected combination of ‘marriage hunting’ and ‘hitmen,’ and I couldn’t help but laugh at the contrast between the two themes. I’m truly thrilled to be playing Kyoko Himekawa, a character I absolutely love!,” said Nagase. “I was immediately drawn to Kyoko’s boldness, straightforward nature, and strong inner core the moment I started reading. I can’t wait for the broadcast to begin… and I hope all of you are looking forward to it as well!”
A businessman of the underworld, Shizuku Ushio (voiced by Mariya Ise) is a Water Master who is very thorough in her work. She completes every task with precision and is always dressed in a diving suit.
“When I first read the original manga, my reaction was, ‘She’s wearing a helmet… and she’s underwater…? How am I supposed to voice her?’ (laughs). I approached the role with the hope of bringing out Ushio’s coolness and mysterious aura, so I hope you enjoy my performance!” Ise said.
Shiori Ureshino (voiced by Asaki Yuikawa) is a college student and the heir to Balzak, a major party supply corporation worth 1.5 trillion yen. Shy and overly considerate of others’ feelings, she is aware of this trait and wishes to change. Her hobby is performing magic tricks, and she loves making people smile.
Yuikawa commented, “Because of her father’s death and the enormous pressure of being the next president of a major corporation, Shiori often finds herself spiraling into negative thoughts. But at her core, she’s an incredibly hard-working girl. Thanks to her own sincerity — and the presence of Gero and the others — she grows little by little throughout the story. Please look forward to seeing how these already charming heroines become even more wonderful as they encounter Gero and move forward together!”
Genya Naruko (voiced by Soma Saito) is the direct descendant of the Sound Master lineage who possesses a unique aura and distinctive way with words. Not only is he extremely handsome, he is highly popular among the ladies. Since he needs to stay relaxed to use his abilities, he’s come up with his own unique ways to unwind.
“As someone who has long enjoyed this series as a reader, being able to participate as the voice of my favorite character is truly a joy,” Saito shared. “We’ve already completed the recording sessions, and the atmosphere was both stimulating and wonderful — I honestly can’t wait to see the finished version.”
Known as a Hamster Master, Kimie Arashiyama (voiced by Hinano Shirahama) is a branch descendant of the Beast Master bloodline. Sirius, her hamster partner, is highly skilled in intelligence work. During her childhood, she was once saved by Gero, which led her to become his secret admirer. She currently works at a small-to-medium-sized advertising agency as she is searching for her long-lost brother.
“It is truly a privilege to be involved in such a fun and wonderful series!” said Shirahama. “Arashiyama is a wonderfully bold and straightforward girl who throws her whole heart into everything she does — but I also find the moments when her delicate side peeks through to be a big part of her charm. With her expressive, ever-changing emotions, and with the unique appeal that shines all the more in a world filled with ‘sound,’ I approached the role with all my strength and passion — with as much energy and passion as Arashiyama herself.”
Piichi Nakagawa (voiced by Simba Tsuchiya) is an ordinary human, but a genetic anomaly with abilities far beyond a Master. He possesses exceptional information-processing skills along with superhuman physical abilities but needs to sleep over 10 hours a day to function properly. However, after sleeping, his body can heal almost any injury or ailment. In terms of pure talent as an assassin, he is among the very best in the modern era.
“To me, Piichi Nakagawa is a character who embodies ‘love’ itself — someone who carries both kindness and madness within him,” Tsuchiya observed. “I hope to express the intense emotions flickering inside him with the same honesty and unfiltered sincerity that define Piichi.”
The new cast members join voice stars Haruki Ishiya (voice of Hikaru Gero), Shion Wakayama (Mei Kinosaki), Haruka Shiraishi (Akari Gero) and Isamu Yusen (Toshiki Hanamaki).
Synopsis: For centuries, the deadly arts have been perfected by those known as the Masters. Among them, the Poison Masters of the Five Great Families hold the most fearsome power and influence. Hikaru Gero, heir to the Poison Masters’ Gero Family, has lived his entire life in the underworld, far removed from love or marriage.
But when the Gero Family head decrees that Hikaru’s sister must bear an heir to preserve the bloodline — by force if necessary — Hikaru resolves to protect her at all costs. It is then that Hikaru encounters Mei Kinosaki, a brilliant marriage swindler who becomes the target of his latest job. Realizing that the only way of solving the family succession problem and protecting his sister is through marriage, Hikaru impulsively asks Mei for help in finding a bride.
“That’s the first time anyone’s ever proposed like that.”
And so, with the cunning marriage swindler Mei as his advisor, elite assassin Hikaru embarks on the most challenging mission of his life: finding a wife! Their goal: the ultimate marriage. This is the world’s toughest mission for love, brought to you by the ultimate duo — an assassin and a marriage swindler!
To win love, you’ve got to play with poison.
A high-stakes mission for the ultimate duo begins!
The MarriageToxin anime series is produced by MarriageToxin Project with animation production by Bones Film and production supervision by Bones, and 3D CG services by Sanzigen and art by studio Bihou. The series is directed by Motonobu Hori, with series composition & script by Kimiko Ueno and character design & chief animation direction by Kohei Tokuoka.
The staff also includes sub character designer Yurika Sako, costume designer Kotono, art designer Toshiki Amata, color designer Hiroko Umezaki, DP Go Kanbayashi, CG animation director Taiki Nagashima, editor Kumiko Sakamoto and composers Tasiei Iwasaki and yuma yamaguchi.
