- Mamiko Noto
- Â Narration / ... 22 episodes, 2018-2021
- Qiege Qin
- Â Dendritic Cell 22 episodes, 2018-2021
- Karen Strassman
- Â Narrator 19 episodes, 2018-2019
- Dorah Fine
- Â Additional Voices 18 episodes, 2018-2021
- Khoi Dao
- Â Cancer Cell / ... 15 episodes, 2018-2021
- Kikuko Inoue
- Â Macrophage / ... 14 episodes, 2018-2021
- Cherami Leigh
- Â Red Blood Cell 14 episodes, 2018
- Robbie Daymond
- Â Killer T Cell 14 episodes, 2018
- Ray Chase
- Â Helper T Cell 14 episodes, 2018
- Erika Harlacher
- Â PA System / ... 14 episodes, 2018
- Erica Mendez
- Â Regulatory T Cell 14 episodes, 2018
- Griffin Burns
- Â Dendritic Cell 14 episodes, 2018
- Kayli Mills
- Â Eosinophil 14 episodes, 2018
- Laura Post
- Â Macrophage 14 episodes, 2018
- Kellen Goff
- Â Mutans / ... 14 episodes, 2018
- Laura Megan Stahl
- Â Naive T Cell / ... 14 episodes, 2018
- Billy Kametz
- Â White Blood Cell 14 episodes, 2018
- Armen Taylor
- Â Cedar Pollen Allergen / ... 14 episodes, 2018
- Morgan Berry
- Â NK Cell 14 episodes, 2018
- Landon McDonald
- Â Streptococcus Pyogenes 14 episodes, 2018
- Xanthe Huynh
- Â Platelet 14 episodes, 2018
- Bill Rogers
- Â Pseudomonas Aeruginosa 14 episodes, 2018
- Erik Scott Kimerer
- Â B Cell 14 episodes, 2018
- Chris Tergliafera
- Â Effector T-Cell 14 episodes, 2018
- Christian La Monte
- Â Neutrophil U-2048 14 episodes, 2018
- Darrel J Delfin
- Â Cancer Cells / ... 14 episodes, 2018
- Ray Carsillo
- Â Additional Voices 14 episodes, 2018
- Kana Hanazawa
- Â Red Blood Cell 13 episodes, 2018
- Tomoaki Maeno
- Â White Blood Cell (Neutrophil) 13 episodes, 2018
- Akinori Egoshi
- Â White Blood Cell (2001) / ... 12 episodes, 2018
- Junichi Yanagita
- Â White Blood Cell (2626) / ... 12 episodes, 2018
- Juri Kimura
- Â Red Blood Cell 3 / ... 11 episodes, 2018
- Kensuke Satô
- Â White Blood Cell (2048) 10 episodes, 2018
- Kentarô Kumagai
- Â White Blood Cell (4989) 10 episodes, 2018
- Daisuke Ono
- Â Killer T Cell 9 episodes, 2018
- Maria Naganawa
- Â Platelet 9 episodes, 2018
- Aya Endô
- Â Senpai Red Blood Cell 9 episodes, 2018
- Saori Hayami
- Â Regulatory T Cell / ... 8 episodes, 2018-2021
- Takahiro Sakurai
- Â Helper T Cell 7 episodes, 2018
- Gakuto Kajiwara
- Â Digestive Tract Cell / ... 7 episodes, 2018
- Hiroki Maeda
- Â Common Cell 1 / ... 7 episodes, 2018
- Shoya Chiba
- Â B Cell 6 episodes, 2018
- Chiaki Kobayashi
- Â Common Cell 2 / ... 6 episodes, 2018
- Anzu Haruno
- Â Platelet 1 / ... 6 episodes, 2018
- Ryôta Suzuki
- Â Killer T Cell 2 / ... 6 episodes, 2018
- Yuka Nukui
- Â Macrophage 1 / ... 6 episodes, 2018
- Chitose Morinaga
- Â Hematopoietic Stem Cell 2 / ... 6 episodes, 2018
- Jun Kasama
- Â Red Blood Cell 4 / ... 5 episodes, 2018
- Manaka Iwami
- Â Platelet 1 5 episodes, 2018
- Jun Fukushima
- Â Bacteria 5 episodes, 2018
- Michelle Marie
- Â Black Lactic Acid Bacterium 5 episodes, 2021
- Akira Ishida
- Â Common Cell / ... 4 episodes, 2018
- Taito Ban
- Â Red Blood Cell 1 / ... 4 episodes, 2018
- Maureen Price
- Â Mast Cell 4 episodes, 2018-2021
- Nobuhiko Okamoto
- Â Dendritic Cell 3 episodes, 2018
- Mao Ichimichi
- Â Eosinophil 3 episodes, 2018
- Ayako Kawasumi
- Â Mast Cell 3 episodes, 2018
- Rikuya Yasuda
- Â Common Cell 2 / ... 3 episodes, 2018
- Meemu Tachibana
- Â Platelet 2 3 episodes, 2018
- Riki Kitazawa
- Â Pseudomonas Aeruginosa / ... 3 episodes, 2018
- Hiroyuki Yoshino
- Â Streptococcus Pneumoniae 3 episodes, 2018
- Kira Buckland
- Â Senpai Red Blood Cell 3 episodes, 2018
- D.C. Douglas
- Â Basophil / ... 3 episodes, 2018
- Yûichi Nakamura
- Â Memory Cell 2 episodes, 2018
- Toa Yukinari
- Â NK Cell 2 episodes, 2018
- Tomokazu Sugita
- Â Basophils 2 episodes, 2018
- Kenji Nomura
- Â Effector T Cell 2 episodes, 2018
- Mariko Higashiuchi
- Â Immature Thymocyte 1 / ... 2 episodes, 2018
- Yui Ishikawa
-  Kôhai Red Blood Cell 2 episodes, 2018
- Shôta Yamamoto
- Â Killer T Cell 1 / ... 2 episodes, 2018
- Mai Nakahara
- Â Staphylococcus Aureus 2 episodes, 2018
- Hikaru Akao
- Â Platelet 2 / ... 2 episodes, 2018
- Daiki Kobayashi
- Â Campylobacter 2 episodes, 2018
- Masaya Matsukaze
- Â Streptococcus Pyogenes 2 episodes, 2018
- Tara Sands
- Â Kyoro / ... 2 episodes, 2021
- Lindsay Sheppard
- Â Additional Voices 2 episodes, 2021
- Tomo Muranaka
- Â Myelocyte 1 episode, 2018
- Mikako Komatsu
- Â Immature Thymocyte 2 1 episode, 2018
- Aoi Ichikawa
- Â Red Blood Cell 1 1 episode, 2018
- Satoshi Hino
- Â Neutrophil Teacher 1 episode, 2018
- Rikiya Koyama
- Â Thymic Epithelial Cell Instructor 1 episode, 2018
- Mutsumi Tamura
- Â Naive T Cell 1 episode, 2018
- Gen Satô
- Â Red Blood Cell 1 1 episode, 2018
- Yû Sasahara
- Â Red Blood Cell 1 1 episode, 2018
- Yuuki Shin
- Â Naive T Cell 1 1 episode, 2018
- Ryôta Takeuchi
- Â Memory T Cell 1 episode, 2018
- Shô Nogami
- Â Red Blood Cell 2 1 episode, 2018
- Daiki Kajimoto
- Â Red Blood Cell 6 1 episode, 2018
- Daiki Hamano
- Â Red Blood Cell 4 1 episode, 2018
- Shûichi Uchida
- Â Red Blood Cell 2 1 episode, 2018
- Kôhei Amasaki
- Â Common Cell 1 1 episode, 2018
- Takayuki Kondô
- Â Blood Transfusion Red Blood Cell 1 1 episode, 2018
- Yû Akiba
- Â Naive T Cell 5 1 episode, 2018
- Masaya Fukunishi
- Â Naive T Cell 6 1 episode, 2018
- Ikumi Hasegawa
- Â Hematopoietic Stem Cell 3 1 episode, 2018
- Hironori Saitô
- Â Blood Transfusion Red Blood Cell 2 1 episode, 2018
- Ayaka Suwa
- Â Child Cancer Cell 1 1 episode, 2018
- Asuna Tomari
- Â Erythroblast 1 episode, 2018
- Shizuka Ishigami
- Â Circulation-kun 1 episode, 2018
- Makoto Koichi
- Â Immature Thymocyte 3 1 episode, 2018
- Naoko Komatsu
- Â Blood Transfusion Red Blood Cell 3 1 episode, 2018
- Natsumi Kawaida
- Â Immature Thymocyte 4 1 episode, 2018
- Yuna Yoshino
- Â Child Cancer Cell 2 1 episode, 2018
- Teppei Uenishi
- Â Common Cell 3 1 episode, 2018
- Itaru Yamamoto
- Â Enteritis Vibrio 1 episode, 2018
- Aimi Tanaka
- Â Immature Thymocyte 5 1 episode, 2018
- Yûsuke Kobayashi
- Â Common Cell 1 1 episode, 2018
- Taichi Ichikawa
- Â Common Cell 5 1 episode, 2018
- Kaito Takeda
- Â Cancer Cell 2 1 episode, 2018
- Makoto Furukawa
- Â Rhinovirus 1 episode, 2018
- Kazuyuki Okitsu
- Â Cedar Pollen 1 episode, 2018
- Kôsuke Toriumi
- Â Bacillus Cereus 1 episode, 2018
- Lucien Dodge
- Â White Blood Cell 2626 1 episode, 2018
- Joe Zieja
- Â Bacillus Cereus 1 episode, 2018
- Yoshitsugu Matsuoka
- Â Bad Bacteria 1 episode, 2021
- Brandon Jay
- Â Campylobacter (2021) 1 episode, 2021
- Henry Mason
- Â Acne Germ 1 episode, 2021