Sun Jun 9, 9:06 AM ET TOKYO (Reuters) - A Japanese man was so enraged by an acquaintance's failure to address him with an honorific that he stabbed the man to death with an umbrella, police said on Saturday. It was the second killing with an umbrella in Japan in less than a month. Ryuji Sakamoto, 32, was arrested Saturday and confessed to killing Takayuki Niimi, also 32, during a Friday night quarrel in the city of Sakuragi, some 170 miles west of Tokyo, police said. "It appears that Sakamoto harbored resentment of Niimi for quite some time because Niimi...