This paper investigates how focus contributes to the phonological and phonetic realization of Japanese intonation. Pierrehumbert & Beckman (1988) pointed out that textual prominence results in the H-tone peak raising on the focused item and IP (Intonational Phrase) initiation before the focused item. Similarly Kori (1989) suggested that the F0 peaks on the words after the focused item tend to be suppressed. Although they give a general description of the characteristics of focus phenomena in Japanese intonation, they fail to explain the F0 peak interaction between H phrasal tone and lexically specified pitch accent in more-than-3-mora words whose accent locations varies from early to late. In this paper, we perform the experiment to investigate the following three points. First, we would like to look at the systematic intonational differences between focused and neutral APs; specifically, focused APs, either accented or unaccented, are compared with the neutral counterparts in terms of F0 pattern. Second, we investigate F0 patterns of a focused AP with more than 3 morae, as the accent of the word varies from early to late. Since an AP with a late accent has a H- on the second mora as well as H*+L on its accent mora, it is expected that these peaks will show systematic F0 pattern when it is focused. Our third concern is F0 patterns of a post focus AP with more than 3 morae, that is, whether a post-focus word is dephrased or just downstepped as the word accent location varies from early to late. This paper is significant in that it tries to clarify the F0 peak interaction between H-and lexical pitch accent H*+L in a variety of focus contexts in Japanese intonation.