roguintsuuchi de fushinna roguin ni kizuku.

means particle

Breakdown of roguintsuuchi de fushinna roguin ni kizuku.

• に: target particle
• 気きづく: to notice
• 不審ふしんな ログイン: a suspicious login

Questions & Answers about roguintsuuchi de fushinna roguin ni kizuku.

How do you break this sentence into parts?

A natural breakdown is:

• ログイン通知 = login notification / login alert
• で = by, through, via
• 不審なログイン = suspicious login
• に = marks the thing noticed
• 気づく = to notice / become aware of

So the basic pattern is:

[means/source] で [thing noticed] に 気づく

What does で mean here?

Here, で marks the means or trigger.

So ログイン通知で means something like:

• through login notifications
• by means of login alerts
• from a login notification

It does not mean location here. It is saying the notification is how you come to notice the suspicious login.

Why is ログイン repeated?

Because the two ログイン words are doing different jobs:

• ログイン通知 = a login notification
• 不審なログイン = a suspicious login

This is very normal in Japanese. The first is part of a compound noun, and the second is the thing being noticed.

So it is not awkward repetition in the Japanese sense.