Japan's best show ever, Abarenbou Shougun (暴れん坊将軍）

Here it is; loads a bit slow though:

暴れん坊将軍
by yuko-isshi

The basic story from what I understood at the time is that the main character is a general that travels around in disguise and rights all sorts of wrongs. Often a friend of his will die during the episode (like in the video here) whereupon he'll have to get revenge. In the end he kills all the bad guys all by himself, or sometimes with a friend or two armed with knives or some other small implements. When he takes his sword out and you hear that ka-ching sound you know the battle's on and all the rest are going to die. The show used to come on at 10 am in Japan (probably still does though the show ended in 2003) and the scene where the music comes on and every bad guy dies was always around 10:40, like clockwork.

That was all I remember from watching it in the morning sometimes in Japan. It turns out that he's Tokugawa Yoshimune (徳川吉宗). Wikipedia also has a good amount of material on what the bad guys say and how he reveals himself:

悪人は「何をほざくか素浪人」、「何をほざくか」、「貴様何者じゃ」、「何者じゃ貴様」、「貴様何奴」、「浪人の分際で…。ここを誰の屋敷と心得ておる!（場合によっては）**の屋敷だぞ!」、「何をほざくか、貧乏旗本」、「はて、何処かで見た顔だが」などと言うが、吉宗の「愚か者（虚け者）! 余の顔を見忘れたか!」、「主の顔を見忘れたか」、「俺の顔を見忘れたか」、「俺の顔をよく見ろ」、「この紋所が目に入らぬか」、「俺の顔を忘れた訳ではあるまいな」などの一喝で吉宗と気付きひれ伏す。鋭い黒幕の場合、稀に吉宗が一喝する前（時にはそれより前。初期はこのパターンが多かった）に「（場合によっては、余だと、まさか、何）…上様!」「上様ぁ～っ…!!」等と自ら気付く場合もあり、「ははぁ、畏れ入り奉りました!」と観念する。この場面では、『水戸黄門』などのように殺陣の途中で家紋入りの印籠などの「身分を明示」するものを見せるわけではなく、殺陣の前に問いただして「顔を思い出させる」パターンが多い。回によっては、幕府直轄の領地（天領）において将軍・吉宗であることを名乗って登場することもある。殺陣の際に刀身の根部の三つ葉葵の紋所を（峰に返すシーンで）見せ付けることもあったが、それはあくまで正体を明かした（悟らせた）後のシーンである。このパターンは「遠山の金さん」にも近い。

And on the English page too:

At the end of about eight hundred episodes, Yoshimune confronts the corrupt official in their safehaven. The official calls his men, but then looking at Yoshimune's face has a flashback leading him to recognize Yoshimune as Shogun and kneel down in obeisance. However, on hearing Yoshimune's demand that he commit harakiri, he declares Yoshimune to be an impostor and orders his men to kill him. Always outnumbered, Yoshimune ends up easily defeating his attackers with the help of his male and female oniwaban. Using the unsharpened back side of his sword so as to injure without killing the corrupt official, he orders his oniwaban to execute him with the words, sei bai.

Sei bai = 成敗