I have now added a bunch of concert dates from 1987 that I was previously unaware of.
On a-ha.com and almost everywhere else, the 1987 Japanese tour in June/July has always been listed with only 7 dates (and several missing venues). But as can be seen on the Japanese a-ha fansite, it turns out that the band actually played 17 concerts.
Megumi, webmaster of the Japanese site, can confirm that all the dates are correct and that none of the shows were cancelled.
And Selina in the UK, who first brought this to my attention, points out that the dates are all listed in the 1987 Japanese tour programme.
So, translated from Japanese, these are the correct tour dates (notice that the Nagoya concert should be June 21st instead of July 21st):
21 June: International Exhibition Hall, Nagoya, Japan
22 June: Nippon Budokan, Tokyo, Japan
23 June: Nippon Budokan, Tokyo, Japan
25 June: Makomanai Indoor Stadium, Sapporo, Japan
27 June: Sendai City Gymnasium, Sendai, Japan
29 June: Osaka-Jo Hall, Osaka, Japan
30 June: Kobe World Hall, Kobe, Japan
1 July: Yokohama Cultural Gymnasium, Yokohama, Japan
2 July: Nippon Budokan, Tokyo, Japan
3 July: Shizuoka City Culture Hall, Shizuoka, Japan
5 July: Kosei-Nenkin Hall, Hiroshima, Japan
6 July: Fukuoka Convention Center, Fukuoka, Japan
7 July: Matsuyama City Hall, Matsuyama, Japan
9 July: Nagano City Culture Hall, Nagano, Japan
10 July: Citizen’s Culture Hall, Yamanashi, Japan
11 July: Niigata Prefectural Civic Center, Niigata, Japan
12 July: Ishikawa Kosei-Nenkin Hall, Ishikawa, Japan
This brings the number of concerts on the 1986/87 world tour up to 169, and the total number of all regular a-ha concerts between 1986 and 2010 is now 564.
(Thanks to Selina, Megumi and Suzie)