The tragic youth love story of Matsumoto Sakutarou and Hirose Aki, as told from the perspective of the 35 years old Matsumoto, still trying to deal with his past. This is the first successful pairing of Yamada and Ayase, the second being Byakuyako.
1) They share the same scriptwriter, lead actors and singers
2) The way to look at past and future of the lead actors are shared. The girl/woman never want to regret for her past but the boy/man is deeply attracted by his past.
3) Both drama are pure love, both their colour are exactly opposite. Sekai is white pure love and Byakyyakou is dark pure love.