TITLE: Reference requests: Jitsuro Nagura
QUESTION [7 upvotes]: I spent some time today looking for any biographical information on Jitsuro Nagura and came up empty-handed. Any suggestions welcome. 
Also, the Wiki note on the Chebyshev $\psi$ function says that von Mangoldt proved in 1895 that
$\psi_0(x) = x - \sum_{\rho}\frac{x^{\rho}}{\rho}- \frac{\xi'(0)}{\xi(0)}-\frac{1}{2}\ln(1-x^2) $
There is a reference to a 1903 note by E. Schmidt which may or may not contain a reference to the original paper, but my amateurish search (in Euclid, JSTOR) did not turn up anything. 
Thanks in advance. 
Edit: have changed the title to reflect that I am seeking information on J. Nagura and have found the other reference. Thanks.

REPLY [3 votes]: There is now available a biographic paper of him:
Daniel Tisdale (2013) Sieve of war: the legacy of Jitsuro Nagura, BSHM Bulletin: Journal of the British Society for the History of Mathematics, 28:3, 143-155, DOI: 10.1080/17498430.2013.793949