Keiji is an special man who is able to see the red string of fate and has hope a lot to see his own string get attached to some cute girl, so when his string is attached to Hiro, a younger classmate he is determined to break that union by force.
I love this story so much. The "Nobody knows what he has until it's not there anymore" theme is really well managed here.
Akai Ito No Shikkou Yuuyo