Coo no Sekai (クーの世界) is a surrealist Magical Realism Urban Fantasy Manga by Oda Hideji. It was serialized from 1999 to 2000 in the seinen magazine Afternoon.
On the eve of her introduction into middle school, 12-year old Renei starts having vivid sequential lucid dreams of another world, filled with nonsensical wildlife. There, she meets doppelgangers of her best friend Ryota and her recently-deceased older brother.
Her brother's doppelganger, calling himself Coo, is charged with escorting Renei "back home". Along for the ride are Ryota's doppelganger (Kyomu), a giant sheep with a skull for a face (Hishi), an animated Talisman (Udo), and a minuscule animated drawing who claims to be the former ruler of the world (King).
Coo's strange world is an unforgiving and vast place, and the group of travelers searches far and wide to find away to free Renei from her nightly trips into their world and to restore her normal dreams . . .
Contains examples of:
- A Day in the Limelight: Part 2 features Renei's grandmother getting an expanded role and becoming a part of the main cast.
- Age-Gap Romance: The 10+ year difference is why Renei turns Coo down.
- Ambiguously Human: Ryota/Kyomu. They act more like an animal, rarely speak, and are the only entities depicted as existing in both worlds simultaneously. Renei notes that she's never Ryota's his parents nor knows where he lives, and he seems to wander the neighborhood by himself at night.
- Death World: Coo's World is incredibly dangerous. Since it's the afterlife, anyone who dies eventually comes back, though.
- Identical Stranger: Coo says that he and Kyomu aren't Renei's brother and friend, but complete strangers. It's triple subverted. Coo IS her brother and lied to Renei in the hopes that she's fall in love with him if they weren't related by adoption. Kyomu, on the other hand - does seem to be a distinct entity from Ryota.
- Unusually Uninteresting Sight: The Monokibiru are a race of small mushroom men who stand around talking and singing. They're a popular snack and humans will often walk up to them and bit their heads off. They react to this with only some annoyance.
- Mundane Afterlife: Coo's World's fantastic setting is grounded by the people, who are all just normal folks that died and adapted to live in a bizarre dreamscape.
- Non-Standard Character Design: Instead of the photo-realism of the other characters, King is drawn like a child's chalk picture.
- No Name Given: Renei's brother's name is never given.
- Not Blood Siblings: Renei and her stepbrother.
- What the Hell, Hero?: The climax of the first half has King arrest, prosecute, and execute Coo for treating everyone so harshly and trying to seduce his underage sister. Since he's already dead, he gets better.
- Wife Husbandry: Renei's stepbrother was inspired by The Tale of Genji to raise Renei as his future wife. Renei admits that she shares his feelings, and that the incest doesn't but her - but the age gap does and turns him down.
