Tokyo Court: Bitcoin Not Subject to Ownership

Layman's gloss (and you should definitely, definitely not try to file a pro se legal action based on my understanding of Japanese property law):

Hypothetically suppose a corporate entity in Japan has physical possession, but not ownership, of property you own. For example, you might be in the business of renting out computers. Subject to standard contractual arrangements, they should not interfere with your ownership of that property. If they, for example, go into receivership and stop paying the lease, the mere fact of them being in receivership does not expunge your interest in the property. You can demand they restore it to you and, if push comes to shove, the Japanese courts / bankruptcy administrator will enforce your claims. (I think the magic words are 取り戻し権 but ask your friendly neighborhood Japanese lawyer about it.)

This generally applies to identifiable, movable real property as opposed to e.g. money or IP. The court found that, since BTC are commingled by nature, it isn't feasible to say that the plaintiff has a cognizable ownership interest in any particular BTC residing on Gox's systems. The plaintiff has to seek recovery through some other legal strategy, most of which will probably come to the conclusion "OK, you get a claim against the bankrupt entity -- welcome to the line and enjoy your pro-rata."

Fun quirk of Japanese bankrupt law: if Gox had loaned you a computer, you'd presently be legally enjoined from giving it back to them even if a Gox officer were to demand the surrender of the computer. You're supposed to hold onto property of theirs until given instructions from the bankruptcy court as to its disposition.