aerialist vs hikikomori

aerialist

noun
  • A specialist in aerials, a freestyle skiing discipline. 

  • An acrobat performing high off the ground, defying a fall to earth, as on a trapeze or a tightrope. 

hikikomori

noun
  • A Japanese phenomenon whereby an individual becomes a recluse from society, typically remaining isolated in a single room at home for a very long period. 

  • A reclusive person of this kind. 

How often have the words aerialist and hikikomori occurred in a corpus of books? (source: Google Ngram Viewer )