Love Letter Day (Rabu Retā no Hi) — "ko (5)," "i (1)," "bu (2)," and "mi (3)" spell out "koibumi," an old word for love letter

What Is Love Letter Day?

Every year on May 23rd is "Love Letter Day." The date comes from a wordplay on the numbers 5, 1, 2, and 3 — "ko (5)," "i (1)," "bu (2)," and "mi (3)" together sound like "koibumi," an old Japanese word meaning "love letter." The day was established by Shochiku Co., Ltd. to promote its 1998 film "Love Letter" (based on a novel by Jiro Asada and starring Takahiro Nakai), and over time it has become a day dedicated to the broader culture of putting your feelings into words for someone you care about. In an era dominated by digital messaging, it's a chance to rediscover the value of choosing your words carefully and writing them down.

A History Woven Through Film and Literature

Throughout human history, love letters have been an essential medium for bridging the loneliness of separation and deepening bonds.

• The influence of the film "Love Letter": When the movie was released in 1998, its portrayal of "a connection across time through letters" resonated deeply with audiences and helped spark renewed appreciation for analog communication.
• A tradition stretching back to the Manyoshu: Historically, the Manyoshu — Japan's oldest poetry anthology, compiled during the Nara period — contains numerous "sōmonka," or exchange poems between lovers. These are essentially ancient love letters, and they show that the culture of conveying feelings through carefully chosen words and imagery has been part of the Japanese spirit for well over 1,300 years.

The Science of How Handwriting Affects the Brain and Heart

Unlike typing on a keyboard, the act of writing by hand strongly activates specific regions of the brain.

• Motor memory and emotional links: When you write by hand, it stimulates the brain's reticular activating system (RAS), which heightens concentration. The fine motor movements of the fingers have also been shown to activate not just the left hemisphere, which governs language, but also the right hemisphere, which governs emotion and imagery.
• Oxytocin and the psychology of handwriting: Psychological research suggests that seeing someone's handwriting can trigger the release of oxytocin — the "bonding hormone" — in the reader's brain, fostering a sense of closeness. Unlike uniform printed fonts, handwriting that reflects someone's individuality more strongly conveys "the presence of the sender," deepening trust on a biological level.

Fascinating Facts About Love Letters

• The meaning behind sealing an envelope: Sealing wax, once widely used in Europe, served as a security feature to protect the privacy of correspondence, but it was also a way for the sender to imprint their personal crest — a sign of both respect for the recipient and the sender's own sincerity.
• The world's oldest known love letter: A clay tablet from ancient Mesopotamia (around 2000 BCE) has been found inscribed with words of love from a woman to a man. Whether the medium is paper or clay, the human instinct to put feelings into a tangible form hasn't changed in over 4,000 years.
• The role of the "P.S.": Short for "Post Scriptum." The words added at the very end of a letter, after the main writing is done, often carry the writer's truest feelings or the thing they most wanted to say — making the postscript a psychologically meaningful accent to any letter.
• The history of professional letter-writers: From the medieval era through modern times, professional scribes existed to write letters for those who couldn't write themselves. Putting feelings into words has historically been considered a highly skilled, intellectual craft.
• "Digital letters" in the modern age: Today, email and social media are the norm, but data shows that messages with strong "staying power" are reread more often and provide more emotional support. The format may change, but the essence of a love letter — careful, thoughtful reflection — hasn't lost its value.

Ideas for Love Letter Day

• On May 23rd (Love Letter Day), try writing a handwritten message card. For someone important to you — at the start of a new fiscal year — convey the subtle nuances that an email or text just can't capture. That extra effort itself becomes the greatest gift you can give.
• Try raising the "resolution" of your words. Instead of vague phrases like "I like you" or "thank you," write down specifically what actions or moments moved you. The process of putting your emotions into language helps organize your thoughts and serves as a form of self-care.
• Treat yourself to a nice letter set or fountain pen. Investing in quality writing tools is a great motivator for producing more thoughtful output — find your "intellectual companion" for putting your thoughts on paper this new fiscal year.
• Reread letters you've received in the past. Revisiting old letters vividly brings back memories and emotions from that time. It's a great way to reconnect with the bonds that support you and to reset from new-fiscal-year stress with some positive recharging.

A Single Line Spilled Onto a Blank Page Can Melt Someone's Loneliness and Become an Eternal Bookmark Connecting Two Futures

May 23rd is a day to put a name to the "feelings you haven't yet expressed" in your heart, and to send them out into the world. In an age of instant digital connection, a message written by hand — taking time to choose your words and feeling the pen glide across the page — carries a weight that nothing else can replace. Amid the busyness of the new fiscal year, are there words you've been holding back from someone important? Today, try carefully writing those feelings down, one character at a time, as a love letter. That single letter could light a flame of courage in someone's heart forever — and in turn, bring you even greater love and trust in return.