A bill to tighten curbs on sexual imagery of minors in comics and animated films will be rejected by the largest force in the Tokyo Metropolitan Assembly, whose session started Tuesday, sources said.

The Democratic Party of Japan and several small groups are threatening to vote down the bill on June 14 unless the metro government retracts it. But Gov. Shintaro Ishihara said Tokyo can come up with a fresh bill if this one is voted down.

With the move, the new bill, which places various bans on comics and animated movies that depict sexual acts involving "nonexistent minors" — a definition of characters that readers or viewers would most likely assume to be under 18 — will likely face further debate this fall.

The bill urges the "anime" animation and "manga" comic industry to impose voluntary restrictions on the sale to minors of works that depict sexual situations involving "nonexistent minors."

It also designates some of those publications that deal with materials such as rape as "harmful materials," and bans minors' access to them.