The International Authority of Baseball & Softball.

Valdemar Terkelsen hit a walk off grand slam to help Denmark beat (12-11) the Czech Republic in the Fastpitch Men softball Challenge Tournament. The game was played in Hørsholm on May 27. Terkelsen was 4 fo 4 in the game (single, single, double, triple), so with the home run he completed a so called natural cycle, getting the 4 different hits in order.
Valdemar Brask Terkelsen was born in 1990, plays first baseman and pitcher and has represented Denmark over 60 times internationally.

There’s no evidence that Terkelsen accomplishment happened before in men softball. In professional baseball a cycle occurred in the history of Major League Baseball (MLB) 307 times, never in the post season. The first one was in 1882 and was hit by Charles Joseph Foley, better known as Curry. He was born in Ireland in 1856 and played in the National League for the Boston Red Caps and the Buffalo Bisons. A natural cycle (“one of the rarest feats in baseball”, according to Baseball Digest) has happened only 14 times. The first to hit for the natyral cycle it was Bill Collins (Boston Doves, National League) in 1910, the last to accomplish the feat was Gary Matthews Junior (Texas Rangers, American League) in 2006.
Cycles are apparently less frequent in NPB (Nippon Professional Baseball, the Major Leagues of Japan). Only 63 hitters hit for the cycle in the history of the Leagues, the most recent being dominican Rainel Rosario
A natural cycle in NPB has happened only 5 times. The first to accomplish it was Fumio Fujimura in 1950, the most recent was Arihito Muramatsu in 2003.
In College baseball, as recently as May 2, utility Junior Jared Atkins hit for the natural cycle for the Taylor University Trojans in a College regular season game against Indiana Southeast-

Terkelsen’s accomplishment remains unique. There’s no evidence a player ever accomplished a natural cycle and walked off the game with a home run, let alone a grand slam.