There are two pieces of info about 東 文彦, same kanji and pronunciation as each other.
https://ja.wikipedia.org/wiki/%E6%9D...96%87%E5%BD%A6
https://ja.wikipedia.org/wiki/%E5%B0...B8%80%E5%A4%AB
According to the second link, 小池 一夫 and 東 文彦 are the pen names of 俵谷 星舟(this is his real name.).
The person of first link(東 文彦 1920~43) has nothing to do with anime.
I made two entries at that time by wrong info that they are not the same person, but recently I realized rechecking some entries.
Sorry for making you confused.
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Edit
東 文彦 is his nickname, 小池 一夫 should be the public pen name as a lyricist, but for unknown reason, both was used on credits.