Shino, 30 years old, is an experienced woman both professionally and emotionally. But today, it is marriage that worries her and she wishes to find a partner who, like her, aspires to settle down. Only Mayuki, a young man nine years younger than her, declares his love to her and enters her life without warning! How can she resist so much spontaneity and fervor? Shino then decides to have a casual relationship with him until she finds the one who will meet her selection criteria...
仕事も恋も、大抵のことは経験してきた森山志乃３０歳。

結婚相手も、一通りやり終えた同年代がいい。そう思っていたのに、９つ下の真雪（まゆき）から突然の告白。そのまっすぐさに惹かれ、志乃に結婚相手ができるまでという条件で、つき合うことになり…？

何歳になったら「要領のいい恋」ができるのだろう。
何歳までなら「もがくような恋」が許されるのだろう。
その答えは、恋してみなければわからない―――！