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If you don't mind me asking, where did you get the Kabashima attribution from? Yuichiro Oguro asked Tsutomu Shibayama about it, and Shibayama confirmed that he himself drew or at least heavily corrected this (and the other scene with Bakabon-Papa).
https://twitter.com/animesama/status/618204039210102784
https://twitter.com/animesama/status/1314641031132934145
Toadette_OTO said:
If you don't mind me asking, where did you get the Kabashima attribution from? Yuichiro Oguro asked Tsutomu Shibayama about it, and Shibayama confirmed that he himself drew or at least heavily corrected this (and the other scene with Bakabon-Papa).
https://twitter.com/animesama/status/618204039210102784
https://twitter.com/animesama/status/1314641031132934145
From atwiki

原画:椛島義夫(背動。荒川眞嗣氏のtwitterより**)
https://twitter.com/Shinjukueyes/status/29376537424
https://twitter.com/Shinjukueyes/status/29377250231

Also, he is credited for OP animation on seesaawiki.
The Oguro-Shibayama posts being more recent I think they might be worth trusting a bit more? At least there's enough to credit Shibayama as well I think
Both are based on statements made by Shibayama, so I think they are both somewhat reliable. Probably the animation director is Shibayama and the key animator is Kabashima.