Reiko Ōta (大田 レーコ Ōta Reiko?) is The Fifth Neck 五の首 Go no kubi and an uncommunicative manga artist whose manga (although successful) have darker themes since she joined the Orochi (whose mark she may wear on her back).
Reiko has straight shoulder-length reddish brown hair that she ties in a loose ponytail with a yellow ribbon, reddish-brown eyes and spectacles with circular lens.
Her outfit is a white one.
Reiko is an antisocial manga artist of few words who continues her "day job" as a member of the Orochi and has in fact done better on the market since joining, though her manga have taken on very dark themes since then. She barely interacts with the other Orochi and is stone-cold in battle, though her level-headedness is more the product of cynicism and numbness than Sister Miyako.
Reiko made her debut in episode 1 when the Orochi arrives and Reiko is usually seen fighting with Corona and drawing for her manga. She attacks the miko in episode 7 along with Nekoko, Girochi and Corona but they are defeated. When Chikane Himemiya became an Orochi, she is petrified by her.
In the flashbacks to the Orochi's pasts, Reiko is seen sobbing her heart out as she discards and marks some manga panels. This implies that she was badly screwed over by the manga industry, which is known for treating many manga artists in rather abusive and exploitative manners: this is likely the reason why she became an Orochi.
Reiko's mecha, Ho no Shuraizuchi, takes on the forms of a Jōmon-style (straw-rope pattern) fired pottery jar and an anthropoid shape. In personal combat, Reiko throws fountain pens at her targets. LikeCorona's lipsticks, these carry a kinetic charge capable of causing explosions. Interestingly, Himeko Kurusugawa adores Reiko's work and she is apparently an avid reader of hers.
- Reiko's surname Ōta means "big, great" (大) (o) and "field, rice paddy" (田) (ta).
- Reiko shares her last name with Hitoshi Ōta, one of the authors of Kannazuki no Miko.
- There is some indication that Reiko carries the mark of Orochi on her back.
- Reiko's seiyu also voiced Rin from Inuyasha.
- Himeko Kurusugawa is a fan of Reiko and her manga (without knowing that she's her enemy).