Ah shit he was missing a shoe

that’s a terrible sign
Not necessarily. Could have come off from her dragging his body.
Honestly, this makes me even more sure that it wasn't a tragic death. The death was a tragedy, but him overworking himself, and his own devil may care attitude to life, makes me think, he had like a a fatal heart condition. Would explain why he was so gung ho about living life to the hardest. Wants to squeeze in as much life as he could, because he understands how precious it is. So even if Tsukiko could probably physically handle it as a beast man, he doesn't want her to live like he did.