Its the Annual I Love My Wife Festivals! (爱妻日)
This is an annual festivals that husband will return home and express their love to their beloved wife!
The festivals is to encourage husband to express their love more often to their most important partners!
31st January is selected for this festivals because “1” is very similar to “I” in character while “31” (in Japanese) sounds like wife thus the date of this festivals is formed in Japan!