Short answer. You appeal to the Regional Trial Court exercising jurisdiction over the area the MTC is in. The case title stays the same as in the court of origin, but the party appealing is now called the appellant and the other party the appellee.
What the law says
An appeal from a judgment or final order of a Municipal Trial Court may be taken to the Regional Trial Court exercising jurisdiction over the area to which the former pertains. The title of the case shall remain as it was in the court of origin, but the party appealing the case shall be further referred to as the appellant and the adverse party as the appellee.
Rule 40, Section 1 — Where to appeal. Read the full provision →
Where the appeal goes
An appeal from a judgment or final order of a Municipal Trial Court is taken to the Regional Trial Court that exercises jurisdiction over the area to which the Municipal Trial Court belongs. There is no other appellate destination available for this kind of case at this stage; the Regional Trial Court is specifically where it must go. Filing the appeal with any other court, including directly with the Court of Appeals, would not satisfy this venue requirement for an MTC decision, and would expose the appeal to outright dismissal on that basis alone, regardless of the merits. The rule ties the correct venue to the Municipal Trial Court's own territorial jurisdiction, so the appellant must confirm which Regional Trial Court actually covers that specific area before filing, rather than assuming the nearest Regional Trial Court is automatically the right one.
The case keeps its title, but the parties get new labels
The title of the case remains exactly as it was in the court of origin; the appeal does not receive a fresh case name of its own. What does change is how the parties are described: the party appealing the case is now referred to as the appellant, and the adverse party becomes the appellee, for purposes of the appellate proceedings that follow. This holds true regardless of whether the original plaintiff or the original defendant is the one who ends up appealing the Municipal Trial Court's decision. Keeping the original case title unchanged also makes the appellate record easier to trace back to the proceedings below, since the case name itself does not shift even though the labels describing each party's role in the appeal now do.
Why this matters
Fixing the correct appellate venue right at the start avoids the wasted time and expense of a misdirected appeal, and standardizing the appellant and appellee terminology keeps the record consistent and easy to follow as the case moves up from the Municipal Trial Court to the Regional Trial Court. Getting the venue and the labels right at the outset keeps the appellate record clean and prevents needless disputes over procedure before the actual merits are even reached, letting the Regional Trial Court focus on reviewing the substance of the decision below.