I have created this guide because I couldn't find information about how to get neither of these items, and I had to go check some japanese guides to find how to do it. I hope this saves you a minute or two.
How to Get a Super Suppressant or Super Stimulant
At the second stage, before you beat the boss of that stage (Hatsuta, the girl in black). You gotta lose that stage so you wake up.
Third floor, behind the brown door, and then the first floor, at the right counter.
You should just go there directly, he will tell you you're laidback or something and send you to get your medicine in the first floor.
The same, but you gotta jump a lot before getting to the doctor. He will comment on that and, as with the super stimulant, send you to the first floor to retrieve the medicine.