TOKYO (AP) — Japan has a plastic problem.In a country where cleanliness and neat packaging have long been considered good service, almost everything, from single bananas to individual pieces of vegetables, pastries, pens and cosmetics is sold plastic-wrapped. But as world leaders descend on Osaka for the two-day G-20 summit that starts Friday, Japan will attempt to become a leader in environmental policy at the same time it plays catch-up with countries that already have well-defined goals in place. In the months leading up to the G-20 summit, Japanese officials have delivered full-throated endorsements of future bans on single-use plastics, beach cleanup efforts and more research into alternatives such as bioplastics.