Seems to use the same archive style as Berserk Musou unknown if they work with Cethleann
samples 

https://drive.google.com/drive/folders/1nZ9HIVkSTVrZ6wYYomceGvfcK8u6yUII?usp=sharing
 

The format is pretty simple. No filenames. Not sure if it works with that Cethleann tool or not.

 

+--------------------------------------------------------------------------------+
| Fist of the North Star: Ken's Rage [XBox 360] LINKDATA.A LINKDATA.B LINKDATA.C |
+--------------------------------------------------------------------------------+

// BIG ENDIAN ORDER

// HEADER
  4 - Header (0,7,125,249)
  4 - Number of Files
  4 - Padding Multiple (2048)
  8 - null
  
// DETAILS DIRECTORY
  // for each file
    4 - File Offset [*2048]
    4 - File Length
    8 - null
    
  X - null Padding to a multiple of 2048 bytes
  
// FILE DATA
  // for each file
    X - File Data
    X - null Padding to a multiple of 2048 bytes

 

also added support for it in my extractor with koei tecmo specific extension guessing:
https://github.com/smiRaphi/UniPyX/commit/385f2da5ce0bd9b194c287b56f591dadbf75716b