Personally I would prefer Japanese because they have a very large industry of voice acting talent in use for anime/game/visual novels which is very difficult to get into so consistently produce very high quality work. I do think the game needs both as in the western gaming environment it has always shown a large majority want English voice overs for Japanese content. Would probably play it in English the 2nd time for comedy if just hear Fuku-San if he can be called on the phone
I am currently learning how to read Japanese Kanji (need to know 1500-2000 symbols to be considered fluent...) and will probably be much further along by the time this game releases so if it is in English I will import it (Will end up having an extra Kickstarter copy
).
The problem is that to many fans of Japanese media including myself this often can be the difference between a purchase as there are quite a number of underlying issues which are left to a 3rd party who often do a poor job such as interpretation of the script (often add superfluous information to make it sound cool...), author's intent in how a character was envisaged to sound (if familiar with original content can be wildly different), voice actors sound and range (i won't even go here...). This may sound a bit obsessive but to those affected they are genuine issues that can significantly hinder getting immersed into the game which after waiting so long i wouldn't want to do.