The Detective Is Already Dead (2021)

Kimizuka Kimihiko has always attracted trouble, so when his uneventful flight turns chaotic, it’s no surprise that a detective is needed. Enter the enigmatic Siesta, a silver-haired girl who ropes him into her investigation as her reluctant assistant. Together, they embark on a globe-trotting adventure, confronting criminal syndicates and averting disasters at every turn. However, tragedy strikes three years later with Siesta's unexpected death, prompting Kimizuka to seek a quiet life in high school. Just when he thinks he’s found peace, a girl resembling Siesta reappears, threatening to upend his newfound normalcy.