赤い糸 means "red thread" and it's somewhat related to "fate".
I've been watching this drama recently and as I thought, it was a sweet and touching drama.
The story revolves a girl and a boy where they celebrate the same birthday.
What is so special about it is that their birthday only comes once in 4 years which means their birthday falls on the 29th Feb.
With the red thread, they believed that it was fated that they are meant to be together as they've met several times before they last found out.
On the other hand, there's a song with the same title which released earlier by Kobukuro and just last year Yui Aragaki made a cover out of it.
The lyrics are really sweet too and I love the PV!
Here I would like to dedicate this song lyrics to all couples out there on this very special day which is Valentine's Day!
The two of us first met here, it was today two months ago wasn't it
i still don't know of a way to kiss you, my first sweet girl friend
our silly little anniversary, i've secretly written on the calendar
"do you know what day it is today?" i asked, a little surprised you answered
"it's my ex-boyfriend's birthday" you said with a smile, your face a little vexed
these were words that were really depressing to my ears, definitely
i can't be compared with the memories of the 3 years you and him had together
but still because i really like you so much, the difference in the number feels so overwhelming
Without an emotional bond, it is merely an exchange that we keep on repeating
until your heart gives an answer, it's better for us to stay apart like this
no matter if it is tomorrow or in the next 5 years, i'll always be waiting here
let's make a promise and tie the red thread in our hearts tightly
the flower that was a bud that time had turned a beautiful colour
but it wilted as autumn passed and it crossed the winter, reflecting how i am right now
time is also too heartless, i am at a loss, under my eyelids
an image of you walking with someone else floats up...
i felt like i might not meet you ever again
how much sooner do i want to meet you
as i keep check on my splitting heart, i believe the answer is now
"can we meet?" written on your letter, your truthful words
were smudged by tears you spilled, i made my way to welcome you back to that place
please don't cry, because today is our first anniversary
let's celebrate it, even if the tight thread had come lose
I merely hope to be loved, don't forget the things you believed in
it's fine even if it is a journey with no goal in sight
let's slowly walk on the path we believe in, with the person we love
note: The song can be found in youtube or under my covers.
Pic originally is the cover of Yui Aragaki's single.