Notes:

source needed
Mister Musashi's on it.
The other image in the set is too NSFW to directly link, so…
Artist's Twitter: @sawatei_
Danbooru tag: sawati
Pixiv account: さわてぃ＠10月まで仕事あり
NOTE: the image was originally uploaded 9/12/2015 to all above sources, so it's a bit farther back.