and It Seems He was Exposed in His Niece's Dungeon Stream.
Jimi na Oji-san, Jitsu wa Eiyuu Deshita: Jikaku ga nai Mama Musou Shitetara, Mei no Dungeon Haishin de Sarasareteta Youdesu
地味なおじさん、実は英雄でした ～自覚がないまま無双してたら、姪のダンジョン配信で晒されてたようです～
Jimi na Oji-san, Jitsu wa Eiyuu Deshita: Jikaku ga nai Mama Musou Shitetara, Mei no Dungeon Haishin de Sarasareteta Youdesu
地味なおじさん、実は英雄でした ～自覚がないまま無双してたら、姪のダンジョン配信で晒されてたようです～
Adaptation
manga
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Keita Sato (41, single) is overworked at his corporate job, dealing with tedious and stressful tasks day in and out. How does he relieve his stress? By sneaking into modern-day “dungeons,” using them as a batting cage, and blasting away ferocious monsters! One day, his live-in niece Hikari secretly follows him and livestreams his adventures, only for his unbelievable strength to go crazy viral!! Keita unknowingly captures the attention of not only viewers, but other big-name streamers. So begins the fantasy tale of an ordinary office worker’s unwitting rise to fame and glory! Source: MANGA Plus