Kojima's father worked for a pharmaceutical company and was an obsessive film fan; from Kojima's childhood he showed him a wide range of films and explained them. The family moved to the Kansai region when his father was transferred for work.
“1963年に東京で生まれ、製薬会社で働く父親の転勤で関西に移り住んだ。映画マニアだった父親は、秀夫が幼いころからさまざまな映画を見せて解説をしたという。”
Kojima regarded the primary family form as a unit of four: his parents, his brother two years older, and himself. After moving from Tokyo toward Kansai, his parents built a house in 1970 in a new development in Hyogo, distant from grandparents and other relatives; Kojima’s father presented that house as where they were starting and from which their children could also begin. They did not have the typical suburban dog because Kojima’s mother had asthma.
“It was during that time that my parents introduced a family tradition: every night we would all watch a film together. I wasn't allowed to go to bed till the film had finished: the opposite of how it is for most children.”
Kojima described his father as a chemist involved in the development of new medicines who, within the corporate structure, was nevertheless a salaryman enduring crowded trains, conflicts with coworkers and persistent fatigue while continuing to work, and who finally managed to buy a house in a Kansai suburb. In that newly created town with no shared past, families and children measured one another by academic background and job title as if playing a card game; Kojima rebelled by choosing the then-young video game industry, where he believed titles weren’t necessary and only a person’s ability mattered.
At 43, Kojima ranked his three vital cultural nutrients as movies, music, and novels. His father loved movies, so Kojima was made to absorb films from the time he began forming memories, and music came along with those viewings; by contrast, although the family home was filled with books and his parents placed children's classics on his desk to tempt him, he still did not read even by the end of elementary school.
In 2001 Kojima went on a whim with his young son to see Crayon Shin-Chan: The Fierceness That Invites the Storm! The Adult Empire Strikes Back and became hooked on the Nohara family from Shin Chan, whose ability to band together in a crisis struck him as a new model of Japanese family. After the birth of his second son his own family grew from three to four, but he admitted he was still not the ideal father: he might have reached the level of the workaholic Hiroshi, while Charles Ingalls remained beyond his reach; he wanted his children to be inspired by their real-life family rather than by television idols.