- Bats Right, Throws Right
- Height 5' 6", Weight 140 lb.
- School Waseda University
- High Schools Marugame Chugakkou, Takamatsu Chugakkou
Osamu Mihara had one of the longest managerial careers in Nippon Pro Baseball history. A member of the Yomiuri Giants in 1936, he hit .209/.370/.302 in 13 games in the fall season that year and .242/.325/.301 in the spring season the next year. A second baseman in his playing days, Mihara finished as a player by hitting .206/.386/.265 in the spring of 1938 abd .215/.331/.299 for Yomiuri that fall. He finished his playing career at .226/.338/.297.
During World War II, Mihara was a private in the Japanese army.
Mihara began his managerial career at age 35 with the 1947 Yomiuri team, replacing Haruyasu Nakajima at the helm during the season. He improved the club from 8th when he took over to 5th. They improved to 83-55-2 and second place in 1948 and won the Japanese Professional Baseball League pennant the next year when they were 48-23-1 under his lead; he missed several months of the season. In 1949, he wrote Kyojin Gun to Tomo ni, a memoir of his Giants days.
After being replaced by Shigeru Mizuhara as Giants manager in 1950, Mihara joined the Nishitetsu Lions in 1951. Throughout the 1950s, his Lions finished under .500 only once, in 1953 (57-61-2). His teams won the Pacific League pennants in 1954 (90-47-3), 1956 (96-51-7), 1957 (83-44-5) and 1958 (78-47-5). The last three clubs all won the Japan Series. His daughter married Futoshi Nakanishi, the Lions' star hitter in 1956.
In 1960 Osamu took over the previously last-place Taiyo Whales and led them to a 70-56-4 season, taking the Central League pennant. It was the only pennant in the club's decades of play. Mihara took them to a Japan Series victory, sweeping the Daimai Orions. The Whales fell back to last the next season at 50-75-5 and through 1967, Mihara's last year as manager, they alternated between competitive second-place finishes and bad fourth- or fifth- place seasons.
In 1968 he moved to the Kintetsu Buffaloes, replacing Akitoshi Kodama. His team struggled the first year, going 57-73-5, but reached second place in the PL (73-51-6), two games behind the Hankyu Braves. In 1970 the club was 65-59-6 and finished third.
1971 found Mihara with a fifth team, the Yakult Atoms. They finished last that year (52-72-6) and then 60-67-3 the next season. The club was renamed the Yakult Swallows in 1973 and Osamu's club was 62-65-3.
As a manager, Mihara was known for atypical moves like removing a player who's 3 for 3 (arguing he was less likely to get a hit yet again), steal while trailing by four runs or bunting when trailing. When these moves worked, it was called "Mihara magic" and was very popular with his players. Other players were highly critical of what they viewed as irrational and unsuccessful strategy. He also aimed for a more homer-friendly style of play than Japan's base-to-base style used previously. Mihara was also a critic of the harsh training methods employed by most NPB teams of the period (he said "I can win without hitting my players"), though he was not a guy to let his young pitchers rest their arms either. He is the manager who used Kazuhisa Inao 18 times in a 27-game stretch to finish 1958 and then six of the seven games in the 1958 Japan Series.
Overall his managerial record was 1,687-1,453-108. He is second all-time (as of 2005) behind Kazuto Tsuruoka in wins and is tied for the all-time loss lead with Sadayoshi Fujimoto. He was inducted into the Japanese Baseball Hall of Fame in 1983.