"A Piercing Heart" (貫く心, Tsuranuku Kokoro) is episode 89 of the Boruto: Naruto Next Generations anime.
Kū tends to Ōnoki, who tries to dissuade Kū from continuing his plans, but Kū continues to believe Ōnoki's weakness is clouding his judgement. Team 10 is exhausted after fighting Kokuyō and wonder how Boruto and Sarada are faring. Caught in Kirara's genjutsu, she controls their movements like a puppeteer. Sarada tries breaking the genjutsu on Boruto with her Sharingan, but Kirara forces him to close his eyes. She wants to play with them like they're dolls, drawing out their injuries. Ōnoki ponders on Boruto's assessment of the Fabrications' will and Kū's own words and actions. He thinks back to first meeting and naming Kū, as well as the other four Fabrications. Ōnoki tries leaving his room, but his path is blocked by an Akuta. The doctor tends to Sekiei's deterioration, and Sekiei asks him how their lives will be after receiving hearts. He's not concerned about being strong, but with protecting his friends. The doctor leaves Sekiei alone with Mitsuki. Sekiei tells Mitsuki he heard of Kokuyō's and Kakō's deaths, and recounts his feelings about it. He asks Mitsuki how that'll change once he has a heart, and Mitsuki explains having a heart doesn't make one human.
Mitsuki relays Kū's orders to the doctor. Having made back from the Sanzu Plains, Sekki has been avoiding the Akuta, and runs into Akatsuchi, who updates him on what has happened. As all other shinobi have been imprisoned, Akatsuchi tasks Sekki with rescuing Ōnoki. Mitsuki shows Sekiei a completed artificial heart. An Akuta updates Kirara on their heart situation. Not wanting to miss it, she makes Boruto and Sarada stop holding back as she leaves. Sarada is able to put herself under a new genjutsu by looking at her Sharingan's reflection on Boruto's sword, then breaks the genjutsu on him. As Mitsuki is about to deliver Kū his heart, Boruto and Sarada arrive. Mitsuki holds them at bay with a Lightning Release, and Kū binds their movement with an Earth Release. Boruto tries appealing to Mitsuki not to help Kū. Mitsuki hands Kū the heart, and while he celebrates, Mitsuki strikes him from behind. Kū drops the heart, revealed to be disguised snakes. All are shocked by the betrayal. They hear explosions from afar, those being Konohamaru destroying the Akuta production site as arranged with Mitsuki. Kurotsuchi frees the captured Iwagakure shinobi. Ōnoki manages to escape his room. Team 7 faces against the remaining Fabrications.
|Boruto Uzumaki||Yuko Sanpei||三瓶 由布子||Sanpei Yūko|
|Mitsuki||Ryuichi Kijima||木島 隆一||Kijima Ryūichi|
|Sarada Uchiha||Kokoro Kikuchi||菊池 こころ||Kikuchi Kokoro|
|Shikadai Nara||Kensho Ono||小野 賢章||Ono Kenshō|
|Inojin Yamanaka||Atsushi Abe||阿部 敦||Abe Atsushi|
|Chōchō Akimichi||Ryoko Shiraishi||白石 涼子||Shiraishi Ryōko|
|Konohamaru Sarutobi||Hidenori Takahashi||高橋 英則||Takahashi Hidenori|
|Kurotsuchi||Hana Takeda||武田 華||Takeda Hana|
|Akatsuchi||Kenta Miyake||三宅 健太||Miyake Kenta|
|Kontsuchi||Fumitake Ishiguro||石黒 史剛||Ishiguro Fumitake|
|Sekki||Keisuke Machiya||町屋 圭祐||Machiya Keisuke|
|Ōnoki||Tomomichi Nishimura||西村 知道||Nishimura Tomomichi|
|Kū||Subaru Kimura||木村 昴||Kimura Subaru|
|Sekiei||Takehiro Urao||浦尾 岳大||Urao Takehiro|
|Kirara||Noriko Shibasaki||芝崎 典子||Shibasaki Noriko|
|Doctor||Tomohisa Aso||麻生 智久||Asō Tomohisa|