TOKYO — The 20th and final pic in the “Diary of a Fishing Fool” franchise — a favorite with Japanese audiences since 1988 — will be released by Shochiku on Dec. 26.

The health of the two stars, both of whom have had heart problems, persuaded producers to pull the plug on the series even though the pics are still crowdpleasers, especially with auds over 40.

Based on a popular comic, the series relates the misadventures of a lazy, fishing-obsessed salaryman and his gruff, if soft-hearted, boss, whom he is teaching to fish.

Rentaro Mikuni, 86, who plays the boss, had surgery for a myocardial infarction on April 28 but recovered in time for shooting to start on June 1.

Co-star Toshiyuki Nishida, 61, who plays the salaryman, had similar surgery in 2003. “The heart-attack twins keep plugging away,” he joked at a press conference.

“Diary of a Fishing Fool 20 — Final,” the first in the series to be shot in Hokkaido, Japan’s northernmost major island, will wrap in mid-June.