They call condoms in Japan コンドーム (\(kondōmu\)).
In Japan condoms are also commonly referred to as ゴム (\(gomu\)), which means "rubber".
コンドーム (\(kondōmu\)), is the most direct loanword from the English "condom" and is widely understood.
ゴム (\(gomu\)) is a more colloquial term for condoms in Japan, literally meaning "rubber," and is also frequently used.
Condoms are a thing in Japan and are commonly available.
Other things that are commonly available in Japan besides condoms are spermicides and oral birth control pills.