In 1600 the Kuroda clan was transferred to Chikuzen Province, and somewhere before or after that Soku moved to Hakata to undertake construction of the public sector such as a castle and castle town, which was shared by Soshitsu and Sotan.
慶長5年（1600年）に黒田氏が筑前国へ移封されると、それに前後して博多に移住し、宗室や宗湛とともに築城や城下町などの整備を受け持った。