Should Buy Diet Pill Back

When I am visited to Japan, I found there have many type of diet pills selling in the drug shop. I was thinking to buy and bring back here, however, I am not dare to get one. All because I do not understand what they writing in the descriptions. I also do not know what ingredients are in the diet pills. If not, sure I will buy some because I heard there diet pills are very effective. Well, never mind, I will get it at my next trip. Although still no idea is when yet.haha