The prequel to this is his time as a ghost... I might not be understanding get your comment correctly? But did you perhaps read reads this before 23:45?
well, technically this is a sequel. The prequel with him as a ghost is 23:45 here on Mangago (=・ω・=)
LOL, I am also a non-native and I went through the same thing, so I sympathise with you so much... If practice is what you want, you can practice english much better with english fanfiction (less probabilities of this happening).
Ah, sorry! I answered to the wrong commwnt!
I'll say this just in case: there *is* a prequel to this manga, though. You can look it up.
They already did. Read this 1st:
http://www.mangago.zone/read-manga/2345/
It's the story of him being a ghost and how he met Iku.
This is a sequel of 23:45. (Re: means Return). The time of him being a ghost you can read it here on mangago. Also the prequel makes more sense than the sequel. Like many others here I'm confused about the sequel.
It would've made more sense if they put his time as a ghost first and then did the memory loss part. But oh well ╮(￣▽￣)╭