As wasurenai and Kaosu Reido pointed out, there is a BE scene in a recent doujin from Studio Kyaun. As Kaosu Reido put it, the main character "goes from basically tiny (B?) to giant (head size) during some 'off screen' BE". If you liked the GREATEST ECLIPSE series done by the same artist, which can be found in earlier posts in this thread, you'll probbably enjoy this as well.
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http://www.badongo.com/file/7557377