There is only one way to read Zi, which is to read the first tone.
Zi: zī
[Zi Zi] Diligent, not slacking off, such as "diligently", "diligently seeking". Original meaning: a two-syllable word "Zi Zi", showing diligence and unremitting efforts.
Such as: assiduously (diligently. Hardworking, tireless); assiduously (diligently, eagerly)
Happy appearance: such as, happy zizi; beautiful zizi.
Wu Zihan is a good name.