Invitation From Hell (地獄からの誘い Jigoku Kara no Sasoi) is the fiftieth episode of Return of Ultraman.
The Underground Science Center was attacked by an unknown force. Later, news reported the suicide of Professor Koizumi. MAT member Ueno, who also was a student of the professor, could not believe the news. He met with Professor Koizumi's daughter and decided to investigate it together, but the professor's daughter kept running into life threatening events. It is all part of the invasion of King Bockle, an underground species that the professor had been researching on!
- Hideki Go (郷 秀樹 Gō Hideki ): Jiro Dan (団 時朗, Dan Jirō )
- Ryu Ibuki (伊吹 竜, Ibuki Ryu ): Negami Atsushi (根上 淳, Negami Atsushi )
- Takeshi Minami (南 猛 Minami Takeshi ): Shunsuke Ikeda (池田 駿介, Ikeda Shunsuke )
- Ippei Ueno (上野 一平, Uneo Ippei ): Hatashi Mitsushi (三井 恒, Mitsushi Hatashi )
- Yuriko Oka (丘 ユリ子, Oka Yuriko ): Mika Katsuragi (桂木美加,Katauragi Mika )
- Fumio Kishida (岸田文夫 Kishida Fumo ): Ken Nishida (西田健, Nishida Ken )
- Jiro Sakata (坂田 次郎, Sakata Jirō ): Kawaguchi Hideki (川口英樹, Hideki Kawaguchi )
- Rumiko Maruno (村野 ルミ子, Maruno Rumiko ): Iwasaki Kazuko ( 和子 岩崎, Kazuko Iwasaki )
- Ultraman (ウルトラマン, Urutoraman ): Ichiro Murakoshi (村越伊知郎, Murakoshi Ichiro )
- Narrator (ナレーター, NaretaAkira Nagoya (名古屋章, Nagoya Akira ) ):
- Doctor Koizumi (小泉博士, Koizumi HakaseSoten Kuni (邦創典, Kuni Soten ) ):
- Chidori Koizumi (小泉チドリ, Koizumi ChidoriTakako Yagi (八木貴子, Yagi Takako ) ):
- Japan Insitude Geology Staff Member (日本地質所員, Nihon Chishitsu Tokoro DokoroiHiroshi Ayukawa (鮎川浩, Ayukawa Hiroshi ) ):
- Return of Ultraman Volume 13 Features Episodes 49-51.