Searching for Walkthroughs and Save Files for your Japanese erogames isn’t so difficult, even with low knowledge of Japanese, IF you use certain Internet sites:
Walkthrough “Browsers”:
http://xgn.jp/
http://www.venus.dti.ne.jp/~nekoneko/
These two sites do not contain Walkthroughs, but give indications regarding their availability elsewhere. To my knowledge, a Japanese equivalent of http://www.gamefaqs.com/ doesn’t exist: you need to search amidst many minor sites -my preferred is http://www.foolmaker.net/game.html - for a specific Walkthrough, but the existence of the above-mentioned sites is a VERY BIG help.
Save Files “Source”:
http://sagaoz.net/savedata/index.htm
This isn’t the only site which contains Save Files, but I’ve always found here all my Save Files, even just for trying random Demo Games (I will reveal you a little secret: if you use the “All Clear” Save Files with certain (rare) Demo Games, you will unlock additional stuff. For example, both demo games from From M and Saiinjutsu hide the same ULTRA BIG surprise… ).
The EroGoddess be praised 
!
! And if this happens, let’s insert 
… ).
… ).