Okay, the user wants me to translate "arrived at maturity" into Japanese. Let me think about the correct translation.
First, "arrived at" can be translated as 到達する or 到着する. But in the context of reaching a state, maybe 到達する is better. "Maturity" here probably refers to a state of being mature, so 成熟 or 成熟期.
Putting it together, "arrived at maturity" could be "成熟に到達した" or "成熟期に到達した". But I need to check which is more natural. Maybe "成熟に至った" is another option.
Wait, the user mentioned if the content is already in Japanese, output it unchanged. But the input here is in English. So I need to translate it. Let me confirm the most natural translation.
Another way could be "成熟した" but that's more like "became mature". The original phrase is about arriving at maturity, so maybe "成熟に到達した" is accurate. Alternatively, "成年に至った" if it's about reaching adulthood, but the original is more general.
I think "成熟に到達した" is the best fit here. Let me go with that.