[1][6][7] Prior to his debut with Arashi, Ninomiya started an acting career when he was cast as Chris for the stage play Stand by Me, which was based on the film of the same name.

Husband of former long-distance runner Akemi Masuda, Yuuji Kiwaki, also participates in operating the newly established company Office Nino, inc.[13][14] On December 16, 2023, he shared on X the link to his official website.

[20] Nino hosts a variety show for TV Tokyo for the first time (and his first appearance in 26 years), "Geki kawa petto dai shūgō!

[21] For 2025, Ninomiya has in mind a fan meeting, which would be his first, planning to visit five locations: Tokyo, Nagoya, Osaka, Hokkaido, and Fukuoka.

The album, Marumaru to Ninomiya to (〇〇と二宮と), debuted at the top spot on the Oricon download ranking within a week of its release.

[31] Ninomiya began his acting career in a 1997 stage play based on the American coming of age film Stand by Me with future bandmates Masaki Aiba and Jun Matsumoto.

However, in 2004, Ninomiya appeared in his first lead role in the stage play Shibuya Kara Tooku Hanarete (シブヤから遠く離れて) directed by Yukio Ninagawa.

[33] He starred as the psychopathic murderer Bruno in Mishiranu Jōkyaku (見知らぬ乗客, Strangers on a Train), which was based on the novel of the same name.

[9] Just a few months before his debut with Arashi, he was given his first lead role in the drama Abunai Hōkago (あぶない放課後, Dangerous After School) with Subaru Shibutani acting as his stepbrother.

!, a boyfriend of a girl who mysteriously shrunk into a size of merely sixteen centimeters tall in the romance series Minami-kun no Koibito (南くんの恋人, Minami's Girlfriend) and a young man who accidentally killed his mother and developed an estranged relationship with his father as a result in the human drama series Yasashii Jikan (優しい時間, Affectionate Time) In 2006, Ninomiya starred in the drama special Sukoshi wa, Ongaeshi ga Dekitakana (少しは、恩返しができたかな, Have I Returned a Bit of My Gratitude?

During the summer of 2007, he and fellow Arashi bandmate Sho Sakurai co-starred together in the manga-based comedy drama Yamada Tarō Monogatari.

[35] After a year without any acting roles, other than a small guest appearance in bandmate Satoshi Ohno's first lead drama Maō, Ninomiya finally took up the main role in the drama Ryūsei no Kizuna "流星の絆 with Ryo Nishikido and Erika Toda acting as his younger siblings.

[36] His Ryūsei no Kizuna role also earned him an Outstanding Actor nomination in the drama category in the 49th Monte-Carlo Television Festival.

The drama special was based on the true story of Bill Porter, an American door-to-door salesman who achieved the highest sales for his company despite suffering from cerebral palsy.

[39] Ninomiya began filming for the drama special Tengoku de Kimi ni Aetara (天国で君に逢えたら, If I Can Meet You in Heaven) in April 2009.

On September 20, 2010, he made a guest appearance on the last episode of bandmate Matsumoto and Yūko Takeuchi's getsuku drama Natsu no Koi wa Nijiiro ni Kagayaku (夏の恋は虹色に輝く, Summer Love Shines in Rainbow Colors).

[9] Ninomiya next took to the screen as Shuichi, a high school student trying to get rid of his abusive stepfather, in the 2003 film The Blue Light with Aya Matsuura as his co-star.

[52] On January 7, 2007, New York Times film critic A. O. Scott listed Ninomiya as an ideal Oscar candidate for Best Supporting Actor.

[54] In 2007, all the members of Arashi co-starred in their third movie together, Kiiroi Namida (黄色い涙, Yellow Tears), with Ninomiya playing the main role of an aspiring manga artist.

On October 1, 2010, the live-action adaptation of Fumi Yoshinaga's award-winning Ōoku: The Inner Chambers manga, which starred Ninomiya and Kou Shibasaki, was released into theaters in Japan.

[58][59] Ninomiya starred as Kei Kurono, a young man who is hit by a subway train and becomes part of a semi-posthumous "game" with other deceased people.

In the 17th issue of Weekly Shounen Jump magazine, it was revealed that Ninomiya would be the voice of Koro-sensei in the 2015 live-action film adaptation of Assassination Classroom.

[63] On 5 March 2016, Ninomiya won the 39th Japanese Academy Award for Best Actor, for his performance in Living with My Mother (Haha to Kuraseba), succeeding fellow Johnny & Associates colleague Okada Junichi.

On July 7, 2024, he announced to his fan club that he would release the compilation of the 123 issues in the form of a book, called "Ninomiya Kazunari no It [itto]", on November 15.

[107][108] True to his joker nature, Ninomiya opened a Twitter account (@nino_honmono) on March 8 2023, posting only written posts, but in the description, the Johnny's Web profile link he put was that of fellow Johnny and long time friend, Shunsuke Kazama, causing amusement on his followers.

[128][129] Green†† 二宮和也のIt [一途] (Ninomiya Kazunari no It [Itto]) (ISBN 408789018X) (November 15, 2024)[101][199] First edition includes a signed photograph bookmark as gift.