Here is another session after another three times failure.
This time, unblock by admin with Admin PIN.
$ gpg --card-edit
Reader ...........: Free Software Initiative of Japan Gnuk (FSIJ-1.1.9-87021534)
00 00
Application ID ...: D276000124010200FFFE870215340000
Version ..........: 2.0
Manufacturer .....: unmanaged S/N range
Serial number ....: 87021534
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Signature PIN ....: not forced
Key attributes ...: rsa4096 rsa4096 rsa4096
Max. PIN lengths .: 127 127 127
PIN retry counter : 0 3 3
Signature counter : 6
Signature key ....: 6E9A 631F 1997 F37C 7F4E 9952 8916 1D16 AA0D B710
Encryption key....: 0138 70C9 FA89 986F 2784 31A9 8AAA 8F21 ABD4 A70C
Authentication key: B2FE 8DAF 9494 3320 760F 38E2 30F6 A992 6870 02D6
General key info..: pub rsa4096/AA0DB710 2016-05-19 Chuji Kunisada
<chuji@gniibe.org>
sec> rsa4096/AA0DB710 created: 2016-05-19 expires: never
ssb> rsa4096/ABD4A70C created: 2016-05-19 expires: never
ssb> rsa4096/687002D6 created: 2016-05-19 expires: never
gpg/card> admin
Admin commands are allowed
gpg/card> passwd
gpg: OpenPGP card no. D276000124010200FFFE870215340000 detected
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? 2
[ Admin PIN ]
[ New PIN ]
[ Repeat New PIN ]
PIN unblocked and new PIN set.
1 - change PIN
2 - unblock PIN
3 - change Admin PIN
4 - set the Reset Code
Q - quit
Your selection? q
gpg/card>
Reader ...........: Free Software Initiative of Japan Gnuk (FSIJ-1.1.9-87021534)
00 00
Application ID ...: D276000124010200FFFE870215340000
Version ..........: 2.0
Manufacturer .....: unmanaged S/N range
Serial number ....: 87021534
Name of cardholder: [not set]
Language prefs ...: [not set]
Sex ..............: unspecified
URL of public key : [not set]
Login data .......: [not set]
Signature PIN ....: not forced
Key attributes ...: rsa4096 rsa4096 rsa4096
Max. PIN lengths .: 127 127 127
PIN retry counter : 3 3 3
Signature counter : 6
Signature key ....: 6E9A 631F 1997 F37C 7F4E 9952 8916 1D16 AA0D B710
Encryption key....: 0138 70C9 FA89 986F 2784 31A9 8AAA 8F21 ABD4 A70C
Authentication key: B2FE 8DAF 9494 3320 760F 38E2 30F6 A992 6870 02D6
General key info..: pub rsa4096/AA0DB710 2016-05-19 Chuji Kunisada
<chuji@gniibe.org>
sec> rsa4096/AA0DB710 created: 2016-05-19 expires: never
ssb> rsa4096/ABD4A70C created: 2016-05-19 expires: never
ssb> rsa4096/687002D6 created: 2016-05-19 expires: never