Strange indeed! The builder's plate (fixed on the vessel before delivery) clearly states Kochi Jyoko, so I can't imagine this must be corret. As it's name suggests, it's located in Kochi (southern Shikoku Island), not in Imabari (in the north of the island) At the time of building, Kochi Jyuko was an independent company. In the mid-1980s Sanko Line, which had ordered over 100 bulkers from a number small & medium yards (including Kochi & Kurushima) went bankrupt, taking many of these yards with it. They were restructured under the umbrella of Shin (new) Kurushima Dock (with headquarters in Imabari), and Kochi became Shin Kochi Jyuko and that's the name it still has (see http://www.skdy.co.jp/english/company/about.html). It's listed there as still having 2 building berths (for 38,000 & 20,000 dwt vessels).
My company delivered equipment for 2 newbuildings there in 1985, but by this time they had hull numbers under the Kurushima system (2525 & 2526)

Builder is Kochi Jyuko K.K. that is on the plate. In Croatian Register of Shipping builder is Kurushima Dock Co., Imabari... Today there is a company named Shin Kochi Jyuko K.K. with almost same logo of company. In mail they said that Ishizuchi was not built and supply from them (Shin Kochi Jyuko)...Very strange situation.
http://www.skj-kk.co.jp/?fbclid=IwAR31y_GLOxE052Ih1LYWUJ4BDyV7piIGrApG587VKlr2Vf-JT3actTB3QDY

LR/IMO No: 7010717 Year: 1970
Name: ISHIZUCHI Keel: 15.9.69
Type: Ferry Launch Date: 10.12.69
Flag: JPN Date of completion: 6.3.70
Tons: 947 Link: 3043
Yard No: 627
Length overall: 72.7
LPP: 65.0 Country of build: JPN
Beam: 13.7 Builder: Kurushima Location of yard: Hashihama
Number of screws/Mchy/Speed(kn): 2D-16
LASTOVO - 1991 - Jadrolinija PO HRV Rijeka

LASTOVO Quite a tricky situation! Builder must be Kurushima Dockyard Co. Ltd., Imabari. Lloyd's Register 1970-71 in its Appendix, Section I 'Shipbuilders and existing ships' shows ISHIZUCHI as Kurushima newbuilding 627. For Kochi Heavy Industries Ltd. there is a remark: No longer Shipbuilders. The last ships built by Kochi were small fishing vessel TOKUJU MARU No.7 (Yard no. 515) and tanker SEIKO MARU (Yard no. 516). So 627 can hardly be a Kochi number. Rgds

IMO 7010717
The Ferry Site has her builder as Kurushima Dock Co., Imabari, but this is incorrect. Kochi Jyuko did become part of the Shin Kurushima Group in the 1980s

Builder's plate: Kochi Jyuko K.K. (Kochi Heavy Industries Co. Ltd.), hull no.627. Built March 1970