[19] On the class group of an imaginary cyclic field of conductor $8p$ and $2$-power degree
(with H. Ichimura), submitted for publication
[18] Normal integral basis of an unramified quadratic extension over a cyclotomic $\mathbf{Z}_2$-extension
(with H. Ichimura), Journal de Th\'{e}orie des Nombres de Bordeaux, 28 (2016), 325-345
[17] On the $2$-adic Iwasawa lambda invariants of the $p$-cyclotomic fields and their quadratic twists
(with H. Ichimura and S. Nakajima), International Journal of Number Theory, 10 (2014), 283-296
[16] On the Iwasawa lambda invariant of an imaginary abelian field of conductor $3p^{n+1}$
(with H. Ichimura and S. Nakajima), Journal of Number Theory, 133 (2013), 787-801
[15] On Hilbert-Speiser type imaginary quadratic fields (with H. Ichimura),
Acta Arithmetica, 136 (2009), 385-389
[14] Examples of the Iwasawa invariants and the higher $K$-groups associated
to quadratic fields , Journal of Mathematics,
the University of Tokushima, 41 (2007), 33-41
[13] Imaginary quadratic fields satisfying the Hilbert-Speiser type condition for a small prime $p$ (with H. Ichimura), Acta Arithmetica, 127 (2007), 179-191
[12] Computation of the $p$-part of the ideal class group of certain real abelian fields , Mathematics of Computation, 76 (2007), 1059-1071
[11] Stickelberger ideals of conductor $p$ and its application (with H. Ichimura), Journal of the Mathematical Society of Japan, 58 (2006), 885-902
[10] The Iwasawa invariants and the higher $K$-groups associated
to real quadratic fields , Experimental Mathematics, 14 (2005), 307-316
[9] Computation of the Iwasawa invariants of certain real abelian fields , Journal of Number Theory, 105 (2004), 235-250
[8] A note on integral bases of unramified cyclic extensions of prime degree. II (with H. Ichimura), Manuscripta Mathematica, 104 (2001), 201-210
[7] On capitulation of $S$-ideals in $\mathbf{Z}_p$-extensions , Journal of Number Theory, 86 (2001), 163-174
[6] Isomorphism classes and adjoints of certain Iwasawa modules , Abhandlungen aus dem Mathematischen Seminar der Universit\"at Hamburg, 70 (2000), 113-117
[5] Initial layers of $\mathbf{Z}_p$-extensions and Greenberg's conjecture , Manuscripta Mathematica, 98 (1999), 477-490
[4] Greenberg's conjecture and the Iwasawa polynomial , Journal of the Mathematical Society of Japan, 49 (1997), 689-711
[3] On the Iwasawa invariants of certain real abelian fields (with H. Ichimura), T\^ohoku Mathematical Journal, 49 (1997), 203-215
[2] On the Iwasawa invariants of certain real abelian fields II (with H. Ichimura), International Journal of Mathematics, 7 (1996), 721-744
[1] On the Iwasawa $\lambda$-invariant of the $p$-cyclotomic field (with H. Ichimura), Journal of Mathematical Sciences, University of Tokyo, 3 (1996), 457-470
[A] Solution of hidden symmetry on the periodic lattice structure (with I. Ario), Journal of Structural Engineering, AIJ, 47B (2001), 31-39