Hello, all. I have what is hopefully an easy question. I recently purchased my first nihontō from a shop in Ginza, which came in shirasaya with separate koshirae. I've since mounted the blade in the koshirae, and I assumed that that tsunagi would replace the blade in the shirasaya. However, the tsunagi doesn't seem to fit, too large for both the saya and the tsuka, and I don't wish to force it.
Is the tsunagi intended to be kept in the shirasaya? As it stands now, I have three loose pieces: shirasaya sheath, shirasaya tsuka, and the tsunagi. In case it's relevant, the sword has been in Southern California for about three weeks, and it's cold and rainy here at the moment.
Any advice would be appreciated -- thank you!