One Path (ひとつの道 Hitotsu no Michi) is the fourteenth episode of Ultraman Mebius.
Teppei's mother discovers that he's a full-time member of GUYS. Meanwhile, the Adjutant's body is infested by a monster larva..
Insectus is attacking, and Teppei attacks with Windom. Windom defeats the monster, but not before it emits a high frequency sound from its chest. Meanwhile, reporters arrive, and Adjutant Toriyama picks unfortunate Teppei for their benefit. His mother, watching television, sees him in uniform.
After his appearance on TV, the Adjundant Aide Toriyama steps in a pile of mysterious goo. Marina warns him that the area has not been decontaminated, and that he should watch where he steps. During this, a small, purple bug emerges from the goo, and climbs up the Adjundant and into his ear. As they walk away, Toriyama tells Maru that he feels like he caught a cold.
Back at GUYS Headquarters, Teppei is surprised to find that his mother has come looking for him. In a panic, he explains to the rest of the team that he has not told his mother about his work with GUYS. The team goes out to try to convince his mother that he is not there. Their attempts fail when George addresses her as "Teppei's Mother" in a song. Becoming suspicious, Teppei's mother confronts the group, just as a violent Toriyama bursts into the room. Toriyama manages to best the team, but Teppei's mother restrains him. During this time, the bug jumps from Toriyama to Teppei's mother.
Teppei explains that when he was young, his mother had a heart attack because he was about to jump out of a tree. He vowed from that day on to never worry his mother again. Meanwhile, his mother is on her way home when she begins feeling ill.
Teppei finds out the reason for Toriyama's violence is because of an Insectus Nauplius, an Insectus offspring that nested in his head. He theorizes that it came from the goo he stepped in, which was really a ruptured egg. The bug is no longer inside Toriyama, and they soon realize that Teppei's mother is infected.
Rushing to his mother's house, Teppei is surprised to find her in a healthy state. The team questions her nany, and find out that she stopped at her husband's hospital on the way home. Meanwhile, a nurse in the hospital notices a locker door ajar. After opening it, she finds a freshly molted Insectus skin.
GUYS soon arive at the scene, and Marina hears the high frequency from before. She deduces that the insect is still inside the hospital, and the team comes up with a plan to kill it. Meanwhile, a giant swarm of insects are headed toward the hospital. The hospital is evacuated, except for all of the immobile patients. Teppei's father stays with them, while his mother finds out about his secret. Teppei defies his mother and goes with GUYS, and they lead Insectus using a replication of the frequency. Insectus recognizes the trap and escapes, molting one last time.
Appearing in its final form, Insectus begins advancing on the hospital. Mirai transforms into Ultraman Mebius and attempts to stop it, but the swarm of insects subdues him. Acting quickly, Teppei uses the frequency to lure the bugs away, and George uses METEOR to put a shield around him. Teppei realizes that the source of the frequency is in Insectus's abdomen, and tells the team to fire on it. It works, and the insects fly away. Mebius continues attacking Insectus, eventually destroying him. Afterward, Teppei's mother realizes that Teppei is not a boy anymore, and lets him stay with GUYS.
- Mirai Hibino/Ultraman Mebius (ヒビノ・ミライ/ウルトラマンメビウス Hibino Mirai/Urutoraman Mebiusu): Shunji Igarashi (五十嵐 隼士 Igarashi Shunji)
- Ryu Aihara (アイハラ・リュウ Aihara Ryū): Masaki Nishina (仁科 克基 Nishina Masaki)
- Marina Kazama (カザマ・マリナ Kazama Marina): Ai Saikawa (斉川 あい Saikawa Ai)
- George Ikaruga (イカルガ・ジョージ Ikaruga Jōji): Daisuke Watanabe (渡辺 大輔 Watanabe Daisuke)
- Konomi Amagai (アマガイ・コノミ Amagai Konomi): Misato Hirata (平田 弥里 Hirata Misato)
- Teppei Kuze (クゼ・テッペイ Kuze Teppei): Kenta Uchino (内野 謙太 Uchino Kenta)
- Shingo Sakomizu (サコミズ・シンゴ Sakomizu Shingo): Minoru Tanaka (田中 実 Tanaka Minoru)
- Aide Toriyama (トリヤマ補佐官 Toriyama Hosakan): Kenichi Ishii (石井 愃一 Ishii Kenichi)
- Secretary Aide Maru (マル補佐官秘書 Maru Hosakan Hisho): Yutaka Maido (まいど 豊 Maido Yutaka)
- Ultraman Mebius Volume 4 features episodes 13-16.