(Chart from Yomiuri Shinbun)

Fantastic (literally) results for flag-waving Liberal (joke) Democratic (joke) Party under the leader whose leadership ability was supposedly proven by fast-eating the pork cutlet on curry & rice and grabbing a train seat from a senior citizen: 294 seats (pre-election 118)
Boy-wonder and Ishihara's Japan Restoration Party which is already talking about working very, very close with LDP: 54 (pre-election 11)
Punishing results for Democratic Party of Japan under the leader who had declared "cold shutdown state" exactly a year prior: 57 seats (pre-election 230)
"Why bothered at all?" results for Japan Future Party under the leader who hid Ichiro Ozawa until very last and who was busy selling her books than campaigning for the candidate who was fighting PM Noda: 9 seats (pre-election 61, mostly Ichiro Ozawa's and Shizuka Kamei's parties)
Noda's gambit to call an election in December did not pay off. He probably underestimated the extent of people's disappointment and probably hatred for his party over the last 3 years, particularly the last 21 months.
While DPJ has been crushed, the guilty party of the Fukushima nuclear disaster all won. Naoto Kan and Banri Kaieda lost in the district election but survived because of the proportional representation part of the election. Yukio Edano, Goshi Hosono, Noda Yoshihiko all won decisively. So did Seiji Maehara.
Noda's Chief Cabinet Secretary Fujimura lost, first time in the election history since 1947. DPJ's "kingmaker" Sengoku also lost. Good riddance. So did Makiko Tanaka, the daughter of Kakuei Tanaka. She apparently lost the support of the backers she inherited from her father, who was a very powerful prime minister of Japan. DPJ couldn't get enough proportional representation votes to have them elected.
Ichiro Ozawa handily won in his district, but his bet on Ms. Kada went very badly for his followers. Ms. Yukiko Miyake, who switched from her own district in Gunma Prefecture to Chiba 4th District to fight PM Noda ended 3rd, out of 4 candidates. Not even close.
Only Ichiro Ozawa and Shizuka Kamei won in the Small District Election, on their own strength, for Ms. Kada's Japan Future Party. Everyone else lost. 7 people won the proportional representation part of the election; none of them was a new candidate under Ms. Kada. Mr. Tetsunari Iida lost both small district and proportional representation, despite his rearranging the proportional representation ranking on the day to submit the document to the election board so that he would be ranked No.1.
Now, Twitter is full of extremely disappointed net citizens busy blaming the generation who get their news from TV and newspaper only and many of whom probably voted for LDP candidates. But from the viewpoints from these people,
After suffering 3 years under DPJ, there is no way they want to allow the party to rule;
But looking around for alternatives, there's only LDP and Komei that they sort of know and are familiar with;
There are people that they've never seen or heard before, from the parties that they never seen or heard before, suddenly coming to their districts and trying to push some fancy-sounding ideas like "graduating from nuke" without details that they can understand.
For them, particularly older people, "Why should we trust these people? They don't even know us, don't know what we need, never worked for us. Now they want our votes?"
But now, the pork-cutlet president of LDP has already declared his first priority is (drum rolls please...):
Change the Constitution.
Why? Because it is his pet project. What does he want to change? Article 9, about Japan renouncing wars. And any reference to "fundamental human rights" Why does he want to do it? Because now he can, he has "the mandate"! But that's a whole another very disturbing and depressing topic later.
I'm seriously worried that the Nuclear Regulatory Authority will be disbanded under the LDP rule, and their scientific, truthful work of examining and recognizing active faults in the nuclear power plants in Japan (in Tsuruga and Higashidori so far) will be nullified.
The only bright spot was Tokyo 8th District, where Taro Yamamoto, though lost to Shintaro Ishihara's ultra-hawkish son who wanted to ban personal radiation survey meters, won more than 72,000 votes despite he had decided to run only one day prior to the start of official election campaign period. He didn't talk about fluffy ideals and future goals, but about children in high-radiation Fukushima, food contamination from radiation, about truly ending the nuclear accident. After the defeat, they are still the specifics he talks about.
Strangely, Japanese Twitter is full of people who accuse Mr. Yamamoto for having run. A lot of Japanese people on the net are screaming the election was rigged. Why? Because the internet polls that they saw all the way up to the election day showed their favorite party Japan Future Party with over 30% (here's one from Reuters, archived).
If Internet polls are correct and true, Ron Paul would be the president of the United States now.