2月10日はにとりの日 にとりの日 2月11日はにとりの日に間に合わなかった人の日
February 10th is [[Kawashiro Nitori]] Day, one of [[Touhou|Touhou Project]] date tags. Since February 10th can be read as "2 (ni) 10 (to)" it's a day when artists draw and post artworks with Nitori.

For those who missed February 10th, there is also a tag called "February 11th is the day for those who missed Nitori Day."
nitori day