Logic Masters Deutschland e.V.

Rules: Place four non-overlapping 3 by 3 regions in the grid such that each region contains the digits 1 to 9 once each. Digits do not repeat in any row or column, including outside regions. Uncircled cells outside regions are empty.
Circles: Place a digit from 1 to 9 into every circle. A digit in a circle counts how many of that digit appear in circles.
Arrows: Digits on an arrow sum to the digit in that arrow's circle. Not all arrow cells need to contain digits. An arrow's circle counts as a circle for the above rule.
Square: The grey square contains an even digit.

Links:
SudokuPad: https://sudokupad.app/jgybwz59qn

If you enjoyed this puzzle and would like to solve a larger and more difficult version, please check out Round totals reclining stucco deconstruction. (8, 7)