Dudes...lemme explain
The title is infact the amount of days roxas was in the organization.
358=1 week short of a year.
Now, as i believe, you spend something like 6 days in twilight town at the start. but, wheres the other day, you may ask.
The day remaining is the day roxas left the organization to search for sora. During that day, he was confronted by Axel, faught with riku, and was put in the alternate twilight town. There is you year. Now
the /2 i believe my represent the second p.o.v of what was happening away from sora. like, the alternate P.O.V of that year. All we really know about that missing year is that sora was asleep. Theres the 1st Point Of View. Roxas, being apart of sora is the second. So, there you have it