How to say "single-handed" in Japanese

• 単身たんしんCommon
  adverb, nounCovers 'single-handed' as being or doing something alone: a person unaccompanied, or an act done unaided. A common word, it typically describes someone living, working, or traveling by themselves.
• 一手にいってに
  adverbCovers 'single-handedly': one person takes on or carries out a task alone rather than sharing it with others. Less common than 単身, it describes how an action is done, not simply that someone is alone.
  何なにしろ小ちいさい店みせなので、彼かれは会計かいけい係かかりから倉庫そうこ係かかりまで多おおくの仕事しごとを一手いってにこなさなければならない。↗

  Because the store is so small, he has to wear many different hats, from accountant to stock boy.

Choose 単身 for the sense of being or acting alone, unaccompanied or unaided, and 「一手に」 for the adverbial 'single-handedly', describing one person taking on or carrying out a task by themselves.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 単身たんしんalone
• 一手にいってにsingle-handedly