First, from the news, as reported by News Post Seven (2/7/2013; my summary, not the literal translation):
Overwhelming number of DPJ politicians wanted Goshi Hosono to run in the DPJ leadership election in December, after Yoshihiko Noda resigned, taking responsibility for the disastrous election result, but Hosono resisted the call. He didn't explain why to the disappointed supporters.
In a gathering in January, Hosono finally told them the reason, that his infant daughter had died right before the December leadership election. According to the source who attended the gathering, Hosono said, "I knew it was the time to put the party first, but I thought it was the time to devote myself to my family, as the father."
According to the source, Hosono's child was due this June but was born 6 months prematurely. Hosono was at his wife at the hospital every day. They named the baby with the name that the family had prepared, and called the baby by the name to encourage her. But the baby died a few days later.
Hosono eventually accepted the position of the secretary-general of the party, a very powerful position, after his wife told him to do so. "You are a politician. Do what you are good at, for the party."
And here are some examples of the reaction (on a togetter) from anti-nuclear net citizens to Mr. Hosono and his wife's personal tragedy. While couching with words like "poor child", they say:
It's probably from eating contaminated rice and contaminated food from Fukushima. He's got what he deserves.
It's nothing but God's punishment.
It's because Hosono is guilty of spreading radioactive materials [in reference to the wide-area disposal of disaster debris].
[Against people who said he should be considerate to a parent who just lost his baby daughter,] So it's OK for such a person to hurt others as long as he lost his daughter? You're crazy.
God's punishment. So it's OK for them to talk like Shintaro Ishihara (who said the March 11, 2011 tsunami was God's punishment), as long as they are against nuclear power.
There are similar kind of tweets over the plant engineering company whose workers were killed in the hostage-taking crisis in Algeria recently. They say the workers deserve the fate, because they work for a company that designs nuclear power plants. They also say the Japanese government sent a government jet to bring the surviving workers home because the company is part of the nuclear industry. (And yes, all these are somehow a sinister plot by the United States.)
Then, these tweets are apparently effectively used by the "other side" to discredit the anti-nuclear people. Then, there are people who attack the person who complied the togetter, calling him "scum" for trying to make people look bad.
"Whatever" is all I can say at this point.