Creating a map-like grid using tikz

Question

Problem

I am planning a trip for vacation and I decided to customize a map of spots I am going to visit using snapshot from Google map.

Specially, I would like to make a grid that looks like the following where there are numbers and letters on the margin so that I could quickly locate particular spot.

I found a solution that serves a different purpose and it gave me the following. It partially solved my problem but I am expecting to add number in the middle (like the previous example).

I am not quite familiar with tikz and some modification does not give me the expected result. I am wondering if someone could help me with this. Thank you in advance!

\documentclass[tikz]{standalone}
\begin{document}
\begin{tikzpicture}
    \node[anchor=south west,inner sep=0] (image) at (0,0) {\includegraphics[width=0.9\textwidth]{map}};
    \begin{scope}[x={(image.south east)},y={(image.north west)}]
        \draw[help lines,xstep=.1,ystep=.1] (0,0) grid (1,1);
        \foreach \x in {0,1,...,9} { \node [anchor=north] at (\x/10,0) {0.\x}; }
        \foreach \y in {0,1,...,9} { \node [anchor=east] at (0,\y/10) {0.\y}; }
    \end{scope}
\end{tikzpicture}
\end{document}

Answer 1

It must be very hot now in Tokyo.

\documentclass[tikz]{standalone}
\newcounter{dummy}
\begin{document}
\begin{tikzpicture}
    \node[anchor=south west,inner sep=0] (image) at (0,0) {\includegraphics[width=0.9\textwidth]{example-image-duck}};
    \begin{scope}[x={(image.south east)},y={(image.north west)}]
        \draw[help lines,xstep=.1,ystep=.1] (0,0) grid (1,1);
        \foreach \x [count=\Z] in {0,1,...,9} { \node [anchor=north,font=\small\sffamily] at (\x/10,0) {0.\x}; 
        \node [anchor=north,font=\small\sffamily] at (\x/10+0.05,0) {\setcounter{dummy}{\Z}\Alph{dummy}};}
        \foreach \y [count=\Z] in {0,1,...,9} { \node [anchor=east,font=\small\sffamily] at (0,\y/10) {0.\y}; 
        \node [anchor=east,font=\small\sffamily] at (0,\y/10+0.05) {\setcounter{dummy}{\Z}\Alph{dummy}};}
    \end{scope}
\end{tikzpicture}
\end{document}