Chase the Miyama Stag Beetle Meitantei Conan : Season 21 Episode 18

The Detective Boys wish to capture a few beetles to bring to school, and as a result, visit Agasa's old friend in the mountains. The Detective Boys manage to find a bunch of beetles at night, but return to find Namatame injured. Namatame's last words are "Miyama Stag Beetle" before losing consciousness.