About EXTENDs:
Each EXECUTOR possesses a vessel for storing life. Its size depends on the character.
As life chips are collected and the like, the vessel fills with life essence...
(The NECESSARY counter falls)
When the vessel is filled a new LIFE is granted--this is referred to as an EXTEND.
Thus, the NECESSARY counter represents the amount needed to fill the vessel.
Achieving an EXTEND also causes the vessel to grow in size.
Thus, with each EXTEND, the next EXTEND moves farther away.
The vessel's starting size and the amount by which it grows with each EXTEND depend on the character.