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.
１９日（土）１３：００～１７：００ 受付 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 ７：００～ オープニングセレモニー（市民ホールつくばね） Opening ceremony at 7a.am ７：３０～ クラス毎に順次スタート 7:30: First race starts. １０：３０～ 競技終了 Finished by 10:30 (probably have to open the road by then to traffic)