Very Difficult or Requiring a Lot of Effort

This page is the CodyCross answer for the clue below from Welcome to Japan, Group 564, Puzzle 2 (Ninja Training).

Question is: Very Difficult or Requiring a Lot of Effort

and the answer is: DEMANDING

Word Meaning:

DEMANDING — Requiring much endurance, strength, or patience.

Definitions from Wiktionary.

Very Difficult Or Requiring A Lot Of Effort - Welcome to Japan CodyCross Answers | CodyCross Solutions