Sakura Wars Windows 10 (サクラ大戦　ウィンドウズ10)

Getting started

Install the Japanese Language Pack for Windows and set Japanese to be the default Unicode.
Acquire disks for Sakura Wars 1,2,3,4.
Download xdelta UI from here.
Download the following zip file and extract it.

Install the program normally.
Use xdelta to apply the "sak.xdelta" patch to "SEGA/Sakura/ADVcore.exe" with "sak.exe" as the output file.
Copy "sak.exe" to the "SEGA/Sakura" folder.
Run "sak.exe".
If you get a "CDdrawFunc::ShowWindow Failed" error, then use DXWnd to run it in a window.

Install the program normally.
Use xdelta to apply the "sak2.xdelta" patch to "SEGA/Sakura2/sakura2/SAKURA2_2003.exe" with "sak2.exe" as the output file.
Copy "sak2.exe" to the "SEGA/Sakura2/sakura2" folder.
Copy "d3drm.dll" to the "SEGA/Sakura2/sakura2" folder.
Run "sak2.exe".
You may have to run it under compatibility mode if you get issues.

Install the program normally.
Use xdelta to apply the "sak4.xdelta" patch to "SEGA/Sakura/Sakura4.exe" with "sak4.exe" as the output file.
Copy "sak4.exe" to the "SEGA/Sakura4" folder.
Run "sak4.exe".

Why doesn't Sakura Wars 3 work? I don't know. I'm working on fixing it but I've not had much luck so far.
Is it available in English The PC version is only available in Japanese for now.
Why are the file sizes for these executables smaller than the ones installed? It is because the SafeDisc 4.60 DRM has been removed. SafeDisc DRM uses the "secdrv.sys" service which is not available in modern windows.
The link to the files doesn't work? Message me and I'll fix the link.
Is this legal? To the best of my knowledge, yes. It is reverse engineering for the purpose of bugfixing and interopability with modern Windows. The games were released more than 15 years ago and it is unlikely that there will be official support released.
How did you get them to work? See here for an explanation.