Itsumi Erika's birthday was on March 6th.

The blank notice in the lower lefthand corner of the 4th panel seems to be an error, so if that ever gets fixed I'll upload a replacement.

Nanashiro Gorou posted on their Twitter about the error (twitter #2029870078137880632), as well as what the missing text should be.

※後ほど赤星小梅さんが手配をしてメッセージはいただけたそうです。
* It seems like a message was received later on after Akaboshi Koume-san made some arrangements.