The 23-year-old forward departs a club that sit top of the J.League, having agreed a four-year deal at the Olympiastadion after the two clubs agreed an undisclosed fee.
Hertha - who finished 11th in the Bundesliga - have been busy in terms of player recruitment since the end of the campaign, with Haraguchi representing their fourth close-season signing.
Versatile midfielder Jens Hegeler, winger Valentin Stocker and defender Marvin Plattenhardt had already signed up for moves to the German capital.
Hertha sporting director Michael Preetz expressed delight at Haraguchi's signing, telling the club's official website: "Haraguchi can be used in several positions across our frontline.
"He can play on the left and the right, in the middle or as second striker. We have a lot of different options now in attack."
Haraguchi, who scored 33 goals in 162 games in Japan's top flight, will once more link up with Hajime Hosogai, a former team-mate at the Red Diamonds.
And Preetz hopes Hosogai can help Haraguchi settle in Germany, adding: "We will give him time. Everything will be new for him here; the continent, the city, the club and the language, but he will be well looked after with Hosogai at his side."
