O (blood type)
Odango Atama -- translated to "dumpling head", this is the nickname given to Usagi by Mamoru after they first meet. Later, Seiya and Haruka begin using it also.
Ofuda -- the word used to describe the anti-evil scrolls that Sailor Mars/Rei Hino uses to ward off evil spirit.
OK Cram School -- The OK Cram School is a cram school that Ami Mizuno attends in episode 027.
Okamachi Noriko -- an actress who appeared in episode 178. She fell in love with Yaten and was attacked by Sailor Iron Mouse for her starseed. Once her starseed was extracted by Sailor Iron Mouse, she turned into the phage Sailor Mademoiselle. Later, she was healed by Sailor Moon. She has red hair and blue eyes.
Once Upon A Time -- a small restaurant frequented by Haruka Tenoh and Michiru Kaioh. Usagi Tsukino and Minako Aino tracked the two of them here under the false impression that Haruka was a handsome guy. The restaurant appeared only in Sailor Moon S episode 92.
Onnanokoha danketsuyo! Jadeite no saigo
Operation Romantic Cruise -- Operation Romantic Cruise is the youma Thetis's scheme to collect energy from humans in episode 012. She and Jadeite advertise a romantic cruise all over Juuban. They then disguised a wrecked ship as a luxury cruise liner, and disguised themselves as members of the crew (Jadeite was disguised as the captain). The ship had a 666 passenger capacity, and tickets were highly sought after. Rei managed to win tickets to board the ship, and she invited Ami. Usagi and Luna snuck aboard using the disguise pen. When the time came to collect the love energy of the humans, Ami and Rei were unaffected. Thetis sent some monsters after them, but Sailor Moon soon arrived on the scene. Thetis attacked Sailor Moon, and while she was distracted, Ami and Rei transformed into Sailor Mercury and Sailor Mars. The two then leapt outside onto the deck and attacked Thetis with their "Sabão Spray" and "Fire Soul" attacks, distracting Thetis long enough for Sailor Moon to destroy her with her "Moon Tiara Action" attack. Once Thetis is destroyed and Jadeite disappears, the ship returns to its normal form as a dilapidated wreck. A coast guard ship soon arrives to rescue the passengers, who have regained their energy.
Orange -- an incorrect spelling of the name of Orangeat, one of the faeries from the SuperS movie. For more information on this character, please see the entry for Orangeat.
Oranjiya -- incorrect spelling of the name of Orangeat, one of the faeries from the SuperS movie. For more information on this character, please see the entry for Orangeat.
Osaka-san -- Naru's mother who owns a jewelry shop. Naru says that she doesn't have much business sense, because when she is having a sale, it must mean that she is finally making a profit.
Oshiokiyo! Uranai house ha youma no yakata
Outer Senshi -- a fan-created phrase which is commonly used to refer to Sailor Pluto, Sailor Uranus, Sailor Neptune, and Sailor Saturn as a group. Their official name is "Gaibu Taiyôkei Yon Senshi," the four soldiers of the outer Solar System.