Ichikawa Haruko Sakuhinshuu

Sumire is a lightning storm. The plane went into him and he accidentally blew it up. He then noticed that Mirai was still alive and wanted to help him survive, so he collected sugar (or maybe ice or glass?) from the clouds and created a skin to contain himself. When Mirai wakes up the next morning, he remembers nothing and Sumire tries to help him get to shelter. He catches the fish with electricity, glows in the night because of it, and moths are attracted to him because he glows, explaining those events.

 

When they finally reach the ocean, Mirai is exhausted and offers Sumire the sugar. I'm not quite sure exactly what happens now but this is my guess: the sugar lights on fire and then he lights on fire. The heat destabilizes Sumire's skin and the electrical burst blinds and harms Mirai. Sumire drags him towards the lighthouse but can't stay for long since he's falling apart. Once he does, he instead lights up the lighthouse for Mirai. Since Mirai is exhausted, he can't make it and falls over the cliff, looking up and seeing a shocked (get it?) Sumire above him. Sumire attempts to save Mirai by grabbing him, but this just fries him instead.

 

When we see the girl get up, it's because her ship crashed the previous night, probably due to Sumire's emotional outburst at Mirai's death. She sees a different girl, Sumire in a new skin, sifting through the water. She thankfully is already near the lighthouse, so Sumire just has to direct her there. Sumire wants to stay behind so that he can continue looking for the only thing left of his friend: the sugar packet wrapper with his name on it.

 

About the names:

I think the name of the chapter is a pun, like Elemhunter suggested (sumire is violet), but just from Violet to Violight. Amano is surname in its own right, so Amano Sumire is a real Japanese name. However, amanasumire is a kind of violet that grows along the coast in Japan. Nothing special about it that I know of, but ama-na/ama-no/ame-no is a fairly common Japanese suffix in traditional mythology that means "__ of Heaven," so this is the "Violet of Heaven." Lightning is a bright violet, so it's quite a neat name for the author to give Sumire. 

 

I can't figure out if Mirai's name is supposed to be special (it means "future"), but I've considered that maybe it's supposed to sound like minai, which is "to not see." In that case it's fitting, as he can't see through much of the story and he doesn't understand anything. However, that's a bit of a stretch.

Kinda reminded me of HNK

Later Edit:

 

Though hoo, boy, that's one hell of a dysfunctional family they're making there in ch. 1.

 

http://www.care2.com/greenliving/sugar-can-make-electricity.html

 

https://en.wikipedia.org/wiki/Orpheus

 

https://en.wikipedia.org/wiki/Izanagi

 

Sumire -> Violet -> Bio-luminescence -> Bio-Light -> Violight