Explanatory Introduction

Whilst searching for a teen hero that wasn't the ubiquitous Robin, dammit, I chanced across the old anime Marine Boy. Further details about him are given in the introduction. In this tale Marine Boy rescues a young diver called Jack, and is overjoyed by the fact that, for the first time in forever, he can hang out with someone who isn't twice his age or more. But are Marine Boy and Jack friends, or more than friends? And is Jack more than he seems, anyway?