Splitting Columns without generating new column

Hii Till__ ,
I tried with the data you provided and it is working perfect.
But I think it will not work if you enter more data but the concept/logic will remain same.
Here is the M code:
let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMqqorFCKjQUA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Test = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Test", type text}}),
#"Extracted First Characters" = Table.TransformColumns(#"Changed Type", {{"Test", each Text.Start(_, 1), type text}})
in
#"Extracted First Characters"


I can help you further if you post more accurate data.