His memory was fuzzy and unable to remember the cause of his death.
It was an old memory, after all.
It might have been a mere accident or pure suicide.
He did not know.
After that, he rebirthed, died, and rebirthed again, a never-ending cycle.
And somehow, his memories remained intact—all compiled into one big library that contained the lives he lived.
Some lives were fulfilling and filled an entire corner of the library; some memories of the series of lives he lived were short and precious and placed in a highlighted shelf that could be easily taken out and read.
After his first death, his first reincarnation was not of the human species, nor was the following rebirth and the next and so forth.