source: [真紅の領域に雛苺のポシェットが入り込んでいると指摘する翠星石のGIF画像｜無料GIF画像検索 GIFMAGAZINE 687564]

very attentive to and concerned about accuracy and detail:

【服装･外見などに】細心の注意を払う, うるさい «in, about»

e.g. he chooses his words with fastidious care.

very concerned about matters of cleanliness:

｟時にけなして｠ «…に» 潔癖な «in, about»

e.g. the child seemed fastidious about getting her fingers sticky or dirty.

fastidiously | faˈstidēəslē | adverb

fastidiousness | faˈstidēəsnəs | noun

late Middle English: from Latin fastidiosus, from fastidium ‘loathing’. The word originally meant ‘disagreeable’, later ‘disgusted’. Current senses date from the 17th century.