To add to Tyler's answer: you'll find that the majority of bureaucrats and public servants are graduates of Todai (University of Tokyo), and gaining admittance to that university is considered the prerequisite to high bureaucratic office in Japan. This actually did not change before and after the War at all.
With any upheaval like the surrender, there will be changes, but the changes are not as extreme as you think.
To give a few more easy examples.
Kishi Nobusuke was the Economic Manager of Manchuko and later Deputy Minister of Munitions in the Tojo cabinet (Tojo was also the Minister, so Kishi effectively was Minister) - he became Prime Minister in the 50's.
Sato Eisaku is Kishi Nobusuke's brother (Kishi was originally surnamed Sato), he became Prime Minister in the 60's.
Hosokawa Morihiro was the grandson of Konoe Fumimaro, who was three-times Prime Minister before the war. Hosokawa himself became Prime Minister in the 90's. The Hosokawa clan was a Daimyo during Medieval Japan, and Konoe was one of the five Fujiwara clans eligible to become regent before the modern Era.
Aso Taro is Prime Minister Yoshida Shigeru's Grandson. Prime Minister Yoshida was a diplomat before the War. He became Prime Minister in the 2000's
Abe Shinzo is Kishi Nobusuke's Grandson, He is the current Prime Minister.
Notorious War criminal (though never tried because they never caught him) Colonel Tsuji Masanobu was elected to the House of Councilors after the war (he showed up in Japan one day after they called off the search).
General Staff Chief of Operations Colonel Hattori Takushiro, Tsuji Masanobu's "partner" during the war, was not only tasked to write the Japanese military history of the war, but was briefly considered to be the organizer of the precursor to the JSDF (recommended by Charles Willoughby no less - but Yoshida Shigeru blocked it.)
Koizumi Matajiro was a Diet member and Minister during the Taisho Period - his son, grandson, and great-grandson all "inherited" his Diet seat. His Grandson is the Prime Minister Koizumi Junichiro.