Anti-whaling group Sea Shepherd's ban on New Zealand activist Pete Bethune attending future protests has caused bemusement in Japan ahead of his last day of trial in Tokyo today.

Bethune faces five charges including assault and carrying a sword after boarding a Japanese whaling ship in protests earlier this year, and is expected to read out his closing statements in Japanese today to show respect for the country.

Most major newspapers and television broadcasters in Japan have picked up on Sea Shepherd's decision to ban Bethune, made earlier this week, with many bloggers trying to make sense of the move.

A discussion thread on website "Tsuruya rengou" kicked off with two expressions of surprise: "E?" and "Huh?".

"Is this the world's joke?" one anonymous poster wrote.

"Protect your mates before you try to protect whales," said another.

One person said it was almost enough to find sympathy for Bethune.

On discussion board 2ch - one of the biggest in the world with more than 2 million posts everyday - one person wrote: "A magnificent betrayal."

"What a filthy organisation," said another.

Bethune's wife, Sharyn, told media yesterday the ban had been intended to help Bethune's trial by distancing him from the protest group, but she questioned the move, saying "I thought the timing was very bad".

Many bloggers focused in particular on Sea Shepherd's statement that it has a policy of "aggressive but non-violent" action.

"There's no greater absurdity than this," wrote a 38-year-old blogger.

"Sea Shepherd's activity so far has been to anyone's eyes 'aggressive and violent' action. Making judgments with a typical, global interpretation, every member of Sea Shepherd would be expelled."

Another blogger, Ryo Noda, wrote: "I have no idea what [Sea Shepherd] is saying. I would like them to explain what specific actions that could mean. An ordinary person like me can't imagine them."

Meanwhile, blogger "flagburner" highlighted his concerns about Japanese protesters outside Bethune's trial.

He wrote of exasperation at the protesters' words, "to let [Bethune] loose would be the same as letting loose a dog with rabies," as quoted in Melbourne's Age newspaper.

"It's too idiotic," the blogger said of the Japanese protesters.

3 News' footage of the protesters was also referenced as unfortunate. "If such footage was seen, all the goodwill Bethune is feeling toward Japan would be wasted."

Comments on the blog said that fundamentally such anti-Bethune protesters were no different from Sea Shepherd anti-whaling protesters.

Japanese newspaper Sankei Shimbun, a national financial daily with a circulation of more than 2 million, picked up on New Zealanders' views of the trial, saying it was a "top class" news item here.

It quoted stories from the Herald, TVNZ and 3 News.

Bethune's trial reopens this afternoon, NZT, and his verdict is expected in one to four weeks.