- In Volume 4, Kuro Identifies the witch as "Hifumi". In Volume Three, The Witch writes "123" when asked to identify herself. In Japanese, the alternate reading of 1 is Hito, 2 is Futa, and 3 is Mitsu, combining to form Hifumi. This also indicates that she may be a creation of the professor, as all his creations (notably Nijuku and Sanju) refer to themselves by slightly off pronunciations of their project numbers.
- This might be confirmed a bit more when the tubes labeled with the numbers one, two, and three in the Professor's lab are cracked open during their minor appearance in volume three's chapter dealing with Nijuku and Sanju's origins.
- On the French Wikipedia page for the series (Le Voyage de Kuro) there is a section that says the twins with the kittens Mo knew were originally Nijuku and Sanju. This goes into details of that after Mo became a victim of the curse and everyone slowly started dying one of the men in white coats was the Professor who took the girls and cats then merged their features and revived them through his scientific practices. A few points in the books do hint this is the case such as the article does reference the single page in volume two where Nijuku and Sanju see a young girl who resembles Mo and say she vaguely looks familiar but they aren't sure from where. Another factor involves the pattern done on the book covers as while Kuro is on the front of each volume Nijuku and Sanju are on the backside of each volume so far except volume six, in their place is the twin girls and their kittens.
Fridge / Shoulder-a-Coffin Kuro