Masumi is fun. He is sometimes angry and holds grudges, but seems to need to be reminded of them. I could provide you with Boukenger and I think you'd enjoy parts, but nobody's really sick. :/ I think you should watch Gekiranger and write a crossover where Higuchi is the Fantastic Mandible, GekiWhite instead. XD;

You could do a Digimon crossover. Higuchi could have a digimon and save the Digital World from plaque.

Other than that, I dare you to write Higuchi/Mello. Or Higuchi/Rem. I have no idea.