I acquired the books from an auction of an estate, two boxes of 100, and many of these works were BL centric pieces from the early 70s to the 1990s. However, there was a plethora of works that were Daimos related, many of which fall under the pieces I've been archiving for some time now. These drawings are traces of various panels, sometimes selectively done, by the individual who owned these books. Give or take, they were more than likely done in 1981, however, some of the books that were traced from are from 1979 especially (volumes of NORMAL in particular), so there could be a range between 1979 to 1981 proper.
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Additional Information:
One distinct theme seems to be that this individual traced them and hid them from view as they were wrapped in a manner that suggested as much and in an innocuous fanzine. I can make out the work of Hiryu Asao and Ryu Hitaka from vol. 2 of Combination Roman Album (https://www.mandarake.co.jp/ariaru/shop/en/item/1069040153)
Included was a sheet of ramblings, poems, and favorite songs, like so: