"If the sun setting there is me, then the sun tomorrow will be you, Ultraman Leo."
- ―Dan Moroboshi to Gen
The Death of Seven! Tokyo is Sinking! (セブンが死ぬ時! 東京は沈没する! Sebun Ga Shinu Toki! Tōkyō wa Chinbotsu Suru!) is the first episode of Ultraman Leo. It features the new Ultra, Gen Otori/Ultraman Leo teaming-up with Ultraseven with Kohji Moritsugu respiring his role as his human form Dan Moroboshi who is also the main cast of Ultraman Leo.
Gen Otori, Ultraman Leo's human form, on Earth, trains at the training place. Meanwhile, Ultraseven is engaged in battle with two twin monsters -- Red and Black Giras. As Seven fights, the master of the two beasts, Alien Magma, appears and tips the scale further in their favor. After his leg is severely fractured by the Black Giras, a new hero appears and saves Seven from certain death. It's Ultraman Leo from the barren Planet L77 in the Leo Constellation. Magma and the Giras Monsters are driven off, but Dan Moroboshi is unable to transform back into Ultraseven.
Dan tells Gen he must protect the earth, and gets him to join MAC (Monster Attacking Crew), of which he is the captain. Gen brings the news of his membership to the sports club. He spends time with Kaoru. He then begins to train the intrepid Ultra, harshly. Soon, Red and Black Giras return, sinking an island.
Gen reports to MAC. He believes Alien Magma is behind the sinking, but no evidence is found. Then the monsters attack Tokyo, devastating it. The sports club flees, but Gen transforms. Leo battles the monsters, but is no match for them.
- Ultraman Leo/Gen Otori (ウルトラマンレオ/おおとり ゲン Urutoraman Reō/Ōtori Gen): Ryu Manatsu (真夏 竜 Manatsu Ryū)
- Seiji Omura (大村正司 Ōmura Seiji): Yu Fujiki (藤木悠 Fujiki Yū)
- Momoko Yamaguchi (山口百子 Yamaguchi Momoko): Kaori Okano (丘野かおり Okano Kaori)
- Takeshi Nomura (野村猛 Nomura Takeshi): Yukio Ito (伊藤幸雄 Itō Yukio)
- Ichiro Aoshima (青島一郎 Aoshima Ichirō): Yuichi Yanagisawa (柳沢優一 Yanagisawa Yūichi)
- Kaoru Umeda (梅田 カオル Umeda Kaoru): Yoshiko Tominaga (富永美子 Tominaga Yoshiko)
- Akio Kuroda (黒田明雄 Kuroda Akio ): So Kuroda (黒田宗 Kuroda Sō)
- Kiyohiko Akaishi (赤石清彦 Akaishi Kiyohiko): Kenji Oshima (大島健二 Ōshima Kenji)
- Haruko Momoi (桃井晴子 Momoi Haruko): Kyoko Aradama (新玉恭子 Aradama Kyōko)
- Junko Shirakawa (白川純子 Shirakawa Junko): Mieko Mita (三田美枝子 Mita Mieko)
- Dan Moroboshi (モロボシ・ダン Moroboshi Dan): Kohji Moritsugu (森次 晃嗣 Moritsugu Kōji)
- Narrator (ナレーター Narētā): Tetsuro Sagawa (瑳川哲朗 Sagawa Tetsurō)
- Ultraman Leo (ウルトラマンレオ Urutoraman Reo) & Ultraseven (ウルトラセブン Urutorasebun): Tatsumi Nikamoto (二家本辰巳 Nikamoto Tatsumi)
- Alien Magma (マグマ星人 Maguma Seijin): Yoshihisa Uragami (浦上嘉久 Uragami Yoshihisa)
- Ultraman Leo Volume 1 features episodes 1-4.
- The Complete DVD-Box features all episodes.
- Strangely, Ultraseven used modified Leo grunts.
- One of the snippets of the civilians escaping is reused from a small number of Showa era Godzilla films (which said films also reuse the snippet).
- The most notable error in this episode is Ultraseven's helmet: His ears are missing on his helmet, and the Eye Slugger was (possibly) not well-adjusted.