Mt Tsukuba is in Ibaraki ken.
This is a quite famous annual hill climb.
12km with 540m of climbing. (The first climb I think is the hardest (400m). IMHO.
I've never done it and don't intend to do it this time either.
The course looks easy but there is a very steep hairpin at about the halfway point and that is usually where weekend warriors stop to check their times.
Just saw the link on a friends blog.
Check in Saturday 19th of June. (registration)
２０日（日） ６：００～ 筑波庁舎駐車場オープン
Car park opens at 6a.am
Opening ceremony at 7a.am
7:30: First race starts.
Finished by 10:30 (probably have to open the road by then to traffic)