In 1989 many Japanese donated money for ~10.000 Sakura Cherry trees because they were happy about the German Reunification. The trees were planted around Berlin and Brandenburg. 1000 were planted at the boarder strip between Berlin-Lichterfelde and Teltow. In April they have Hanamis there.
Every year in April we have Hanami (german: Kirschblütenfest) in different locations in Berlin, f.e. you can go to the Hanami and Cosplay event in Gärten der Welt in Berlin Marzahn-Hellersdorf, Eisenacher Str. 99, 12685 Berlin
The roof of the Sony Center in Berlin represents Mt. Fuji or Fujisan. - Das Sony Center soll eines der Wahrzeichen Japans, den heiligen Berg Fujisan, symbolisieren. Nach japanischem Glauben wohnen die Kami (Naturgeister oder -gottheiten) in den Bergen, da Berlin jedoch in dem Sinne keinen Berg hat, wurde kurzerhand das Sony Center als künstlicher Wohnsitz für die Kami gebaut, damit Sony auch in Europa im Schutz dieser steht.
The Japan Festival Berlin is every year at the end of January in the Urania, An der Urania 17, 10787 Berlin-Schöneberg. One Day Ticket: ca. 15€. It's great there, you can shop a lot of anime and kawaii stuff, watch cultural shows like a Kimono fashion show, taiko drum perfomance, japanese martial arts and so much more. Visit!!! An be early, it get's crowded.
If you want to meditate and practice Zazen: Zen Dojo Berlin e.V., Mehringdamm 57, 10961 Berlin, http://www.zen-berlin.org/de/dojo-berlin/ - There are other clubs and dojos for Zen or Zazen in Berlin too.
If you want to learn and train kendo, naginata, jodo, laido... You can get a member at the club Kenshinkai Berlin e.V.: http://www.kenshinkai-berlin.de - There are a lot of other clubs who are providing japanese sports in Berlin too.
Berlin and Tokyo are Partner Cities, you can get informations about events on the english and german website: https://www.berlin.de/rbmskzl/en/international-relations/city-partnerships/tokyo/artikel.23728.en.php - f.e. they organize a marathon exchange in both cities, so that Germans can take part in the Tokyo marathon and the other way around