Chaji is a full tea presentation with a meal. As in virtually every tea ceremony, the host may spend days going over minutiae to insure that this ceremony will be perfect. Through tea, recognition is given that every human encounter is a singular occasion which can, and will, never recur again exactly. Thus every aspect of tea must be savored for what it gives the participants.
Milk in Japanese tea would probably lead to blows with swords.
;-)
Cheers,
Scott.