  We present a new model of $\mathcal{N}{=}\,8$ mechanics with semi-dynamic
supermultiplets. The model is constructed as an interaction of
$\mathcal{N}{=}\,4$ supermultiplets which carry an implicit $\mathcal{N}{=}\,4$
supersymmetry. The initial field content consists of three dynamical $({\bf 1,
4, 3})$ multiplets: one bosonic and two fermionic. To ensure implicit
$\mathcal{N}{=}\,4$ supersymmetry, we introduce the superfields describing
three semi-dynamical $({\bf 4, 4, 0})$ multiplets: one fermionic and two
bosonic. To avoid the second-order Lagrangian for fermions from the fermionic
$({\bf 1, 4, 3})$ multiplets, the conversion of their velocities into new
auxiliary fields is carried out. After conversion, these multiplets turn into
semi-dynamical mirror $({\bf 4, 4, 0})$ multiplets without non-canonical terms
in the $\mathcal{N}{=}\,8$ Lagrangian at the component level. The final
$\mathcal{N}{=}\,8$ multiplet content is $({\bf 1, 8, 7}) \oplus ({\bf 8, 8,
0})$. As a first step to the ultimate $\mathcal{N}{=}\,4$ superfield
formulation of the model, we remind a natural description of the standard and
mirror $({\bf 4, 4, 0})$ multiplets in the framework of $\mathcal{N}{=}\,4,
d{=}\,1$ biharmonic superspace.
