Two volumes, by Kamo Nabako, published by Japan by Biblos (BExBOY Comics). Mostly lighthearted yaoi stories, featuring Hijikata Toshizo x Okita Souji, but there’s other pairings as well. Unlicensed outside of Japan, and out-of-print, but not hard to find.
Volume 1 ISBN 4882718936
Volume 2 ISBN 4835210107