しか(shika) — "Only" (with Negative, Insufficiency)

• 財布には百円しか入っていない。

  Saifu ni wa hyakuen shika haitte inai.

  There's only 100 yen in my wallet.

  百円 + しか + negative verb (入っていない).

• 英語しか話せません。

  Eigo shika hanasemasen.

  I can only speak English.

  Apologetic nuance: "Unfortunately I can only speak English, nothing else."

• 教室に学生が一人しかいません。

  Kyoushitsu ni gakusei ga hitori shika imasen.

  There is only one student in the classroom.

  一人 + しか + negative verb (いません) — regretfully, just one.

• ・Crucial Rule: しか must attach to a grammatically NEGATIVE predicate (あります → しかありません).
• ・Emotion (しか vs だけ): 百円だけある is a neutral fact; 百円しかない is a resigned realization ("I only have 100 yen left…").
• ・しか usually absorbs and replaces は/が/を.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones しか is tested against.

• は (wa) — Topic & Contrast Particle
• が (ga) — Subject Marker & Exhaustive Listing
• を (o) — Direct Object & Traversal
• に (ni) — Target, Time, and Existence Location
• で (de) — Context of Action (Location, Means, Condition)
• と (to) — And (Exhaustive), With, and Quotation
• か (ka) — Question, Or, and Uncertain Identity
• の (no) — Possession, Modification, & Nominalization