OK, that makes sense I just remember reading the story about it getting torpedoed and the sub crew couldn’t believe it sank.
https://en.wikipedia.org/wiki/1_November_1944_reconnaissance_sortie_over_Japan
On November 1, 1944 a B-29 recon plane flew a photo mission on one of the very few crystal clear days over Tokyo.
Japanese freaked, everyone in the city saw the silver plane flying back and forth but it was too high for fighter interception (They tried) or for their AA guns.
One of only 2 photographs that survive of the supercarrier Shinano were taken on this mission.
The Japanese navy decided it was too dangerous to complete the carrier in Tokyo and rolled the dice to finish it in the Inland Sea (Kure). They lost.