Here is a Riddle x Ace little copy-bon doujinshi! The only slightly explicit part is on page 11. Scanned by me (Adorable Doujinshi Scanlations) https://adorable-scanlations.blogspot.com/?zx=be08eff7fb921401
scan #408
Suruga-ya link - https://www.suruga-ya.jp/product/detail/ZHONA251641
direct download link - https://www.mediafire.com/file/8im064awdhlrakh/%2528%25E6%2581%25A5%25E3%2581%25AF%25E9%2581%2593%25E9%2580%25A3%25E3%2582%258C%2529_%25E3%2582%25A8%25E3%2583%25BC%25E3%2582%25B9%25E3%2581%258F%25E3%2582%2593%25E3%2581%258C%25E5%25A4%25B1%25E6%2595%2597%25EF%25BC%2588%25EF%25BC%2589%25E3%2581%2599%25E3%2582%258B%25E8%25A9%25B1.zip/file