dataSource.getRepository(EstateModel).find({
     relations: ['city', 'pref']
});

    LEFT JOIN `E_PREF` `EstateModel__EstateModel_pref` ON 
                       `EstateModel__EstateModel_pref`.`PREF_ID` = `EstateModel`.`PREF_ID`
    LEFT JOIN `M_CITY` `EstateModel__EstateModel_city` ON 
                      `EstateModel__EstateModel_city`.`CITY_ID` = `EstateModel`.`PREF_ID` AND
                      `EstateModel__EstateModel_city`.`PREF_ID` = `EstateModel`.`PREF_ID`

    LEFT JOIN `E_PREF` `EstateModel__EstateModel_pref` ON 
                       `EstateModel__EstateModel_pref`.`PREF_ID` = `EstateModel`.`PREF_ID`
    LEFT JOIN `M_CITY` `EstateModel__EstateModel_city` ON 
                      `EstateModel__EstateModel_city`.`CITY_ID` = `EstateModel`.`PREF_ID` AND
                      `EstateModel__EstateModel_city`.`CITY_ID` = `EstateModel`.`PREF_ID`

@Entity({name: "M_ESTATE"})
export default class EstateModel {
	@PrimaryGeneratedColumn({name: "ESTATE_ID"})
	id!: number;
	@Column({name: "ESTATE_NAME", type: "varchar", length: 100, nullable: false})
	name!: string;
	@Column({ name: 'PREF_ID', comment: '都道府県ID' })
	prefId!: string;
	@Column({ name: 'CITY_ID', comment: '市区ID' })
	cityId!: string | null;
	
	@OneToOne(() => CityModel)
	@JoinColumn([
		{ name: 'CITY_ID', referencedColumnName: 'id', },
		{ name: 'PREF_ID',  referencedColumnName: 'prefId'}
	])
	city!: CityModel | null;
	@OneToOne(() => PrefModel)
	@JoinColumn([
		{ name: 'PREF_ID',  referencedColumnName: 'id'}
	])
	pref!: PrefModel | null;
}

@Entity({name: "E_PREF" })
export default class PrefModel {
	@PrimaryGeneratedColumn({name: 'PREF_ID'})
	id!: string;
	@Column({name: 'PREF_NAME', nullable: false})
	name!: string;
	@Column({name: 'PREF_KANA', nullable: false})
	kanaName!: string;
}

@Entity({name: "M_CITY" })
export default class CityModel {

        @PrimaryColumn({ name: 'CITY_ID', nullable: false })
	id!: string;

	@PrimaryColumn({ name: 'PREF_ID', nullable: false })
	prefId!: string;

	@Column({ name: 'CITY_NAME', nullable: false })
	name!: string;
}

dataSource.getRepository(EstateModel).find({
     relations: ['city', 'pref']
});