a joint surety / co-signer who is jointly and severally liable for a debt or obligation (can be directly held responsible by the creditor)
賃貸契約では親が連帯保証人になることが多い。
For rental agreements, parents often act as joint guarantors.
銀行はローンの審査で連帯保証人を要求した。
The bank required a joint guarantor during the loan screening.
連帯保証人になれば、借金の返済義務を負うことになる。
If you become a joint guarantor, you take on the obligation to repay the debt.