Born as the second son to a family of three brothers, Kenta was always seen by his mother Rina as a quiet, easygoing child who didn't assert himself much. However... when his older brother moved out for work and his younger brother left for baseball boarding school, Kenta found himself living alone with just his mom. Their once lively household became eerily silent, leaving Rina feeling lost. Seeing her distress, Kenta felt guilty and empty, yearning to reclaim the love and affection he had never fully experienced before. Determined to make things right between them, he decided to take matters into his own hands...

3人兄弟の次男に生まれた健二。母親・りなからすると自己主張をしない静かな子という印象だったのだが…。ある年の春、兄は就職して1人暮らし、弟は野球進学で寮制の学校に入学。父親は単身赴任と慌ただしく生活が変化して健二とりなの母子2人暮らしが始まった。賑やかな家が急に静かになり、喪失感を感じるりな。そんな母の様子を見て、健二は悔しさと虚しさを感じ、今まで独占できなかった母親の愛情を取り戻そうとして…。