We reported in a previous paper the discovery of large-scale structure of Lyman \alpha 
emitters ( LAEs ) at z = 4.86 \pm 0.03 
with a projected size of 20 h _ { 70 } ^ { -1 } Mpc \times 50 h _ { 70 } ^ { -1 } Mpc in narrow-band data of a 25 ^ { \prime } \times 45 ^ { \prime } area of the Subaru Deep Field ( \Omega _ { 0 } = 0.3 , \lambda _ { 0 } = 0.7 ,H _ { 0 } = 70 h _ { 70 } km s ^ { -1 } Mpc ^ { -1 } ) .
However , the surveyed area , which corresponds to 55 h _ { 70 } ^ { -1 } Mpc \times 100 h _ { 70 } ^ { -1 } Mpc , was not large enough that we can conclude that we are seeing a typical distribution of z \simeq 5 LAEs .
In this Letter , we report the results of follow-up imaging of the same sky area using a new narrow-band filter ( NB704 , \lambda _ { c } = 7046 Å and FWHM = 100 Å ) to detect LAEs at z = 4.79 , i.e. , LAEs lying closer to us by 39 h _ { 70 } ^ { -1 } Mpc on average than the z = 4.86 objects .
We detect 51 LAEs at z = 4.79 \pm 0.04 down to { NB 704 } = 25.7 , and find that their sky distribution is quite different from the z = 4.86 LAEs ’ .
The clustering of z = 4.79 LAEs is very weak on any scales and there is no large-scale high-contrast structure .
The shape and the amplitude of the angular correlation function are thus largely different between the two samples .
These results demonstrate a large cosmic variance in the clustering properties of LAEs on scales of \sim 50 h _ { 70 } ^ { -1 } Mpc .