Alexander Koji Murofushi is the eldest son of Shigenobu Murofushi, who was a famous hammer thrower, known as the "Iron Man of Asia".

Murofushi entered Narita High School (Narita city, Chiba Prefecture, Japan) at the age of fifteen, where he tried out various athletic sports, under the famous manager, the late Tsuguo Takita. He started hammer throwing under his father's careful guidance. The first record of his life in a competition was 44.26 meters in April 1989, just after entering high school. He threw with a double spin form, using a 14-pound (6.35kilogram) hammer for high school students.

In 1991, he set a new high school record, 68.22 meters with a 14-pound (6.35kilogram) hammer and achieved the best high school 61.76 meters with a 16.01-pound hammer in his second year. In 1992, his senior year, he marked 73.52 meters with a 14-pounder, and also set the high school best 16-pound record 66.30 meters. He also won the inter-high competitions in 1991 and 1992.

In 1993, Koji Murofushi enrolled in Chukyo University, where his father taught (and still teaches). In April, 1995, he became the third Japanese hammer thrower to break 70 meters, recording 71.02 meters at the Gunma Relay Carnival. He held top place at the Inter college competition championship for four years. Murofushi set the Junior Japan Record, the Student Record and many other records.

He enrolled in the Chukyo University Graduate School of Physical Education in 1997, at the same time as he entered Mizuno Corporation, and he is taking advantage of the advice and guidance of professors there in his studies and throwing. In April 1998, he marked 76.65 meters in Gunma Pefecture, breaking his father's long held national record. In August at the World Championships in Athens, he made it into the finals and broke open the door to the world.

Though Murofushi had been a leading Japanese hammer thrower since he was teenager, in May 2000, he broke 80 meters for the first time, throwing 80.23 meters and winning the Osaka Grand Prix. This made him one of the top athletes in the world. In June 2003 in Prague, he set a new record of 84.86 meters, the third place world record at that time, and the best world record in the past 15 years. He placed first in the Grand Prix, Golden League, Grand Prix final, Good-will Games, and others. These were amazing achievement for Japan.

In the 2001 World Championships, Murofushi got the silver medal after a well matched game with Szymon Ziolkowski (Poland). Overcoming an injury right before the 2003 World Championships, Murofushi received a bronze medal. At the Athens Olympic in 2004, he became the first Japanese athlete to win a gold medal in a track and field event other than a marathon since World War II. He was the first Japanese male to win a medal since Naoto Tajima, the triple jumper at Berlin Olympic in 1936.

Now he is focusing on the Beijing Olympics and at the same time finding synergy between his athletic studies and athletic activities. He also hopes to be able to benefit the track and field worlds and society in general, in return for all he has received.