What I know about Japan from reading Japanese crime fiction 2

(Part 1 here)

Even though I've only spent about three weeks in Japan, I've really got to understand the land from reading Japanese detective stories.

• Japanese rooms are typically fitted with locks whose keys are impossible to duplicate. They may be imported from a firm in Europe, or they may be hand crafted. The essential point is that it should be impossible, even for the owner, to make a copy. 
• On leaving this world it is considered good form to leave a hint as to your murderer. (Japanese murderers generally give their victims a chance to leave a message before they go.) If possible, you should go for something less brutally direct than the name. Something allusive in the arrangement of objects on your desk might do, or a few riddling letters that need to be combined with your known interests in poetry or art history before a meaning can unfold. Etiquette guides tell us that on receiving Japanese visiting cards, one should look at them for a few moments before putting them away. During these moments you should be thinking, 'Just supposing I end up getting murdered by this person, what would be an elegant way to suggest their name to the investigators?'
• Academics in Japan have very understanding employers. They have an awful lot of time that they can use as they like. Generally they like to spend it in the company of Japanese police, perhaps because they too have the kind of easygoing employers who let them do what they want with their time.
• The gardens of Japanese houses may contain a tiny separate house of one or two rooms, the hanare. Don't sleep in the hanare.