Legumentine's is a holiday in the Hatoful universe that takes place on February 4th. Girls are encouraged to buy packaged beans and give them to the bird they like. The tradition began as a combination of the Japanese Setsubun, or Bean-Throwing Ceremony, and the Western Valentine's Day. The name Legumentine's, then, comes from combining "legume" and "Valentine's."
According to bird history, mamemaki, practiced druing Setsubun, was originally a ritual of throwing soybeans at pigeons on February 4th, though in reality the beans are thrown at a family member dressed as an oni or outside the house in order to banish ill fortune. The real-world Setsubun is also actually held on February 3rd.
Readers of Golden Weekly have been known to send beans in to the publishing office addressed to their favorite manga characters.
The High Society Seagull Department Store sells bean varieties for the holiday as part of their Legumentine Fair.
In the Hatoful manga, Hiyoko gives a blend to all of her friends at school as a token of friendship. She also gifts Tohri a package of leftover "emergency beans" to stop him from hoarding all the Legumentine's bean supply and keeping others from participating out of jealousy.