Sekai ka Kanojo ka Erabenai

One day, Kouki Nakagawa was determined to declare his love to Ayumi Fujisaki, his childhood friend. Suddenly, a mysterious girl appears before them and mentions that she is Kouki's girlfriend, leaving both perplexed. After trying to talk to Ayumi again, Kouki confesses his love to her; But Jindou, the mysterious girl, appears to warn Kouki that if he does not accept to be her boyfriend and does not forget Ayumi ... The world will be destroyed!

Note: Includes 5 extra chapters.