Article 5. With regard to any lease contract relative to fishery as actually existing at the time of enforcement of this Law, except for the case where its leasee has effected any rental default or other non-bona fide acts, or where it has been leased merely for a transient period, or where the contents thereof have ceased to be proper because of changed situations, or where other justifiable reasons exist therefor, the person concerned shall not cancel or terminate the lease contract (including the termination by mutual consent), nor refuse any request for renewal.