In 2010, a display in a bookstore marking the 120th anniversary of Agatha Christie’s birth re-hooked Kojima and led him to reread her major novels to find out what had fascinated him as a child.
Kojima said that as a child he did not read and that he rejected reading without having tried it. In fifth grade he picked up Murder on the Orient Express because there was a film adaptation and he only wanted to see what the book was like; the novel struck him, sparked his curiosity, and led him to read almost all the Agatha Christie he could find before reaching middle school.
After Publish or Perish, Kojima began slipping away alone to the bookstore opposite the tutoring school and felt that spending time among the books meant he had entered the adult world. He awaited each monthly Columbo novelization and went to the bookstore weekly even when no new book had come out, to the point of wondering whether he was really attending the tutoring school or the shop. There he discovered Agatha Christie and Ellery Queen, which opened the way to mysteries, science fiction, adventure, and his future profession.
If he had to preserve a single Agatha Christie novel, Kojima would choose And Then There Were None. He admired that a locked-room mystery in which everyone dies could work and that its premise, its misdirections and its final twist still surprised contemporary readers.
Kojima continued to consult the annual guide Kono Mystery ga Sugoi not so much to find new books as to check whether the books he had chosen for himself appeared on the list. In 2012 he congratulated himself for recognizing the top entries until he came across Hiroko Minagawa, an author he had not read; this wounded his pride as a daily visitor to bookstores. After learning that Minagawa, now eighty-two, also walked inside a bookstore every day, he delightedly opened The Resurrection Fireplace and immediately proceeded to read two more of her works, Shi no Izumi (Fountain of Death) and Toritsu Suru To no Satsujin (Murder at the Upside-Down Tower).
Kojima compared Christie’s novels to quiz shows and video games: brisk reads of precise length and density that focus on dilemma and deceit rather than leaving a depressive social or emotional burden. He argued that, as with action or puzzle games, readers learn her patterns with practice and engage in an intellectual contest with the author, though Christie will defeat them again if they become complacent.