Operation Red Book

A hot-tempered, sentimental and arrogant Chinese girl x a shy, rational and withdrawn British boy (the male and female protagonists are not a couple, but pure friendship and partnership) Ivy, a Chinese girl who immigrated to the UK, and Joshua, a nerd who is not familiar with her at all, traveled through time, bowler hats, crinoline skirts, and whizzing steam trains... Huh? They actually traveled to the Victorian era of the 19th century! "I saw you fall directly from above!" Joshua appeared in front of Sherlock Holmes out of thin air. "You are the first suspect in this case!" Ivy was directly pointed out as a suspect by Holmes. "Let me think, are you a vampire? Or an angel who fell into the mortal world...