It is the only film where Shiki's character is not seen using her habitual kimono dress with a leather jacket on top. She uses a blue school uniform because she is doing undercover work with Azaka Kokutou.
Azaka Kokutou was the prototype for Akiha Tohno in Lunar Legend Tsukihime. Both girls are uptight, snobby, have brother complexes, and an uncanny distaste for their brother's choice of company. In Type-Moon's Plus Period Artbook, Azaka Kokutou is the spitting image of Akiha Tohno except that Akiha has a significantly flatter chest.
Timeline: January 1999.