J'axhe Rhaadne

 <button class="tablinks" onclick="openCity(event, 'London')">London</button>
 <button class="tablinks" onclick="openCity(event, 'Paris')">Paris</button>
 <button class="tablinks" onclick="openCity(event, 'Tokyo')">Tokyo</button>

London

London is the capital city of England.

Paris

Paris is the capital of France.

Tokyo

Tokyo is the capital of Japan.