(Internet slang, especially anime and manga fandom) events or things from the past which one wants to whitewash/erase from history (due to it being embarrassing, poorly received, etc.); dark past

oral history

historicism

a research student (i.e. a visiting or non-matriculating graduate student) / a researcher

researcher

a laboratory

researcher

research association; research society / group of enthusiasts (as may be found in schools, colleges, etc)

research & development; R&D

(education) research project, done by Japanese schoolchildren during summer break, to be presented upon return to school