User blog comment:GinIchimaru/399: Deicide/@comment-1904799-20100408221159

Aizen Sorrow, while I think there's more to Gin's bankai than what we've seen, Toshiro's comment to Kira was most likely referencing the ability we HAVE seen, which is the 13 kilometer blade.

I thought it was weird that Gin said "bankai" in Chapter 398 but had to say it again in 399. Probably a minor error, but still, it was a little confusing for me.