The people at the Chinese consulate in Osaka are generally a pain to deal with and will look for any excuse to get rid of you without having to do any paperwork. The best example of this is that they will attempt to refuse all applications for L visas, insisting that all applications must be made as part of a tour group... Arming oneself with printed regulations and being able to argue in Chinese or Japanese will generally get one of the girls behind the counter to acquiesce and accept the forms, but it's always a battle.

The best approach, in my experience, is to employ the services of one of the agencies across the street from the consulate. They'll be able to get you pretty much whatever you want if you pay enough (including two-year F visas and fake[?] invite letters), and should certainly be able to pull off a lowly transit visa for a reasonable charge.