Samurai! Pirates! Betrayals! Spies! "Ghost ship" is a book with teenagers in mind that everyone can enjoy. Osaragi goes for adventures with prototypical characters and does a good job of it, but, with little originality in the proceedings, its energy just can go so far.
Jirōmaru's father has died. Because of that, he goes to visit his uncle. On his way to Kyoto with his dog, he meets teenager Oniyashiya, who tells him of the dangers of the capital. On arriving to the capital, unable to find his uncle's house, he gets into an empty one to pass the night. There he meets a woman and a rōnin who seems to be following her. Pretty soon he discovers that the woman is on the run and that the actual ruler of Kyoto has an eye on her, as she is the daughter of the former ruler.
Cue adventures, spies, secrets, a mystery, and all the elements of your typical adventure book. Jirōmaru is good enough as the hero, but Osaragi doesn't center just on him and the rōnin Samanosuke or Oniyashiya also get their moments of glory. It is fast paced, easy to read, and its only objective is to help the reader pass a good time. This is its strongest and, at the same time, weakest point. It is always fun, never boring, things keep happening and you will worry for every one of the characters. At the same time, it is something you have seen many times before, from the bad spy to the 'princess' or the samurai with a good heart and the characters lack depth.
With the second part still to read, ゆうれい船 (1st part) is fun, but won't make you want to become a samurai.