The Blood Donors is a fan-term used to refer to a trio of unnamed characters, along with Curie whose shared racial trait between them is that they feed on blood to survive.
The trio consists of the unnamed Mosquito-girl, the unnamed Lamprey Mermaid-girl and the unnamed Leech-girl, all of whom debuted in Chapter 49 of the manga.
Following the Extra Species Cultural Exchange Exhibition it is shown that the three girls, plus Curie, live together in their own apartment.
- The unnamed mosquito-girl is dressed like Shimakaze from Kantai Collection.
- In her introduction, the unnamed mosquito-girl was originally shown to have only two arms, but later in the Omake, as well as the second OAD's endcard, she is shown to have four arms.
- This was eventually corrected with Volume 12's release, where the mosquito-girl is consistently depicted with four arms.