Board Thread:News and Announcements/@comment-26818662-20160620083347/@comment-26044227-20160620214342

People are usually able to guess because of the design of the sword's crest, as well as other themes visible (for example, every Toushirou's been guessed because of their crest + uniform, Nihongou was guessed because of the crest and the spear, etc.)

But this time people are more conflicted. The crest is almost unmistakably a reference to the Date clan's family crest, which makes people suspect that it's the long-awaited Taikogane Sadamune (Sada-chan). However, there's really not that much else to go on, and since there's no clear "taiko" or "bell" motif going on, a fair number of people think it might be another Date sword altogether, or even a sword owned by Uesugi Kenshin named Himezuru Ichimonji, who bears a similar family crest and would better fit the feathers/jewel decoration on the teaser since Himezuru is "Crane Princess."