In his second year of middle school, Amano Yukiteru struggles with loneliness and a lack of companionship. Finding solace in documenting his observations in a cellphone diary, he envisions an imaginary friend named Deus Ex Machina, the supposed Lord of Time & Space. Witnessing Yukiteru's desolation, Deus grants him a unique ability—the power to foresee imminent events in his diary. Subsequently, Yukiteru becomes embroiled in a high-stakes game where the victor will inherit Deus's mantle. This concise OVA accompanies the eleventh manga volume's limited release, offering a glimpse into Yukiteru's enthralling journey.