[kj1980]

Originally Posted by Matrim

Spoiler:

If not, he was missing at the time so presumably he was in some other place or had a means to survive the spread of the volcanic gas because he knew it would happen.

Spoiler:

And yes, the anime missed another minor detail:

Oishi: "I had a stomach ache and took a day off from the investigation right before that fateful day."

That's the difference between how Oishi survived in Himatsubushi, but was listed as missing in Tatarigoroshi