Kasama, a historic town known for its pottery production, holds a large garden located on a hill top, blessed with stunning views of 8500 Azalea trees. The flowers are usually in full bloom between the end of April and the beginning of May, when this festival is held. Kasama-inari, a shrine with a history of 1350 years, also has a large tree of glorious Wisteria that will be in full bloom around the same season.

Kasama Tsutsuji (Azalea) Festival 
笠間つつじまつり

April.15(Sat) - May.7th(Sun) 2017

Location: Kasama Tsutsuji Garden, Kasama City, Ibaraki Prefecture

The admission of the Azalea garden is 500 JP Yen/adult. 

YouTube by Kasama Channel
Kasama Tsutsuji Festival https://youtu.be/KjyCZjyn7ys

Kasama Tourist Association (Japanese webpage)
http://www.city.kasama.lg.jp/page/page006147.html

Getting there  From Tokyo(Ueno Station) by train
From JR Ueno Station 上野 take the Joban-sen Train 常磐線 and get off at Tomobe Station 友部 to change trains. From Tomobe Station take the Mito-sen train 水戸線 and get off at Kasama Station 笠間. (Total travel time 2 hr 7 min. Fare 1950 JP Yen)
Or
From JR Ueno Station 上野 take the Utsunomiya-sen Train 宇都宮線 and get off at Oyama Station 小山 to change trains. From Oyama Station take the Mito-sen Line and get off at Kasama Station 笠間 (Total travel time 2 hr 14 min. Fare 1950 JP Yen)

Note that taking a Tokkyu express train requires extra fee and the fare will almost be doubled.

From Kasama Station to Kasama-inari shrine it takes about 20 minutes on foot. From Kasama-inari shrine to the Azalea garden is a 30-min walk.