The purpose of this study is following two points.
1. Check a function of the implosive marks.
2. Consider the pronunciation of the t-implosive in the Middle Ages in Japan.
As a result of examination of this study, the next points became clear.
1. The "急入声点" implosive marks are added to the t-implosive and the assimilated sound.
2. The "緩入声点" implosive marks are added to ki/ku/fu-implosive sound.
But the texs that these implosive marks were added were extremely limited.
Furthermore, Shinran(親鸞) who was a scholar of those implosive marks, did not add those marks in the texs which in the kanji kana mixture sentence.
From the above mentioned situation, when it was limited, the t-implosive was realized.
Therefore, we must not think that the t-implosive was kept in all cases of the Japanese Chinese word until an end in the Muromachi era.