✾ Please also check my profile ✾ 22-volume set of Gakken Manga's Secrets Series. Many of the first editions are from the 1970s to the 1980s. The information written is old, but I enjoyed the nostalgia of the pictures and expressions. I bought them used 4-5 years ago. There is a lot of deterioration on the covers and stains on the page edges, but most of the insides are clean.