While studying at Zengyo Junior High School, Ogasawara played for the Shonan Boys where in his last year with team he helped them to win the annual Giants Cup.

He pitched a winning 161 ball game in the final against Sendai Ikuei Gakuen High School as well as hitting a solo home run in the 9th inning to clinch the title.

The Dragons would eventually prevail in acquiring the star high school pitcher, in a lottery with the Fighters, and won the right to negotiate a contract.

[11][12] On 7 June, Ogasawara would be robbed once again of his maiden win this time against the Orix Buffaloes as Shinji Tajima gave up a run in the 9th inning to even the scores.

[13] On 16 June, Ogasawara would lose his first game as a pro after pitching 5 innings conceding 7 hits and 3 earned runs against the Chiba Lotte Marines[14] resulting in his de-registering from the first team.

[18][19] On 7 August, in another game against the Yokohama DeNA Baystars, Ogasawara formed a combined rookie battery with number 3 2015 draft pick Takuya Kinoshita; the first time in 18 years for the Dragons (the last being Kenshin Kawakami and Fumihiro Suzuki in 1998).

[27] Ogasawara's following start against the Yakult Swallows at Meiji Jingu Stadium on 18 September would also result in a win where he threw down 6.2 scoreless innings with 6 strikeouts, 6 walks and 4 hits to help the Dragons climb off the bottom of the table.

In Fall training however, after being pushed to throw over 200 pitches in one day, he suffered from cartilage damage in his left elbow and required surgery effectively ruling him out for the entirety of the off-season.

[50] He shares the same hometown as team-mate Shuhei Takahashi and the two attended the same elementary school and played at the same junior baseball side Shonan Boys.

[53] He has remarked on his admiration for Masahiro Yamamoto formerly of the Dragons and Hiroki Kokubo former Fukuoka SoftBank Hawks infielder and then manager of the Japan national baseball team.

[54][55] Ogasawara also has great respect for former New York Mets and San Francisco Giants outfielder Tsuyoshi Shinjo hoping to emulate his success.