Volume 5 of the Le Papillon Single Cask Japanese Whisky series from Mars Whisky has now been released: P.maacki, common name alpine black swallowtail.
Looking at the whisky, we can see it's slightly over 4 years old, spending its days in Shinshu in American White Oak, cask #1870. Bottled at 60% abv in August of this year. Per the label, there are only 560 bottles of this one out there.
Like The Lucky Cat May, Le Papillon P.maackii appears to be another stealth release, given that Hombo Shuzo still has no information about this one on their homepage or on their webstore. Rather, this one went directly to retail and bars. So if you got lucky, chances are you've already picked up a bottle, or your local bar has. For the rest of us who don't or can't visit liquor shops everyday, it's only now appearing on auction sites like Mercari. In fact, thanks to this guy for the pic -- in return I've linked your auction!